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Make Your Movie - Thaumatrope

What to do

1. Cut a circle from a piece of cardboard.
2. On one side draw a head with an apple on it.
3. On the other side of the cardboard, draw an arrow (or pick two other related pictures like a fish and a fishbowl).
4. Use sticky tape to attach the circle onto a straw.
5. Roll the straw back and forth between the palms of your hands, while you look at the cardboard. What do you see?

What's happening

Modern movies use technology to produce an optical illusion and fool our brains.

When you look at a picture, your eye and brain retain the image for a fraction of a second after it has gone. This is called persistence of vision.

If you are shown more than ten pictures a second, your brain will merge the separate images into a series of moving images.

Motion pictures show 24 still frames per second that give the illusion of smooth motion. The brightness of an image also affects the length of time the image will remain in your brain.

The Soap - Propelled Boat

What you need

To do this experiment you will need the following:

• thick cardboard or thin plastic (like the lid of a margarine container)
• scissors
• a large shallow bowl or a baking dish full of water
• dishwashing liquid
• a toothpick, pencil or eye dropper.

What to do

1. Carefully cut out a boat shape from the cardboard (around 8 centimetres long by 6 centimetres wide).
2. Cut out a triangular notch at the back of the boat with the triangle pointing towards the back of the boat.
3. Gently place the boat on the water in the dish.
4. Using the pencil, toothpick or dropper, place a drop of detergent into the notch at the back of the boat.
5. Watch your boat zip across the water!

What's happening?

It looks like the boat is being pushed along by the detergent, but in fact it is being pulled by the water in front of it.

In many liquids, the molecules of the liquid are attracted to each other. This attraction makes the surface of the liquid act like a stretched-out balloon skin. Any point on the surface of a liquid is under tension. In water, the tension is only very slight and it is fairly easy to break through the surface, but if you have ever done a 'belly-flop' into a swimming pool, you have felt the effect of surface tension.

Different liquids have different amounts of surface tension. A mixture of water and detergent (or soap) has much less surface tension than water.

Normally, surface tension pulls the boat in every direction.

When you add the detergent, the surface tension at the back is reduced. The tension at the front pulls the boat forward. The triangular notch helps the boat drag a little bit of the detergent with it, so it travels further.

You may find the boat only works once or twice. This is just because the water mixes with the detergent you have dropped in, so the surface tension of the water in the container is reduced and it can't pull the boat as well.

Degree Celcius - Thermometer

What you need

To do this experiment you will need to gather:

• a tomato sauce or mayonnaise squeeze bottle. You can also use a plastic container or bottle with a water-tight lid but you will need to make a hole in the lid.
• plasticine or adhesive putty
• a clear, narrow drinking straw
• food colouring
• a waterproof marking pen
• water
• a wooden skewer, wire, or pipe cleaner (optional)
• an eye-dropper (optional).

What to do

1. Half fill the bottle with water and add a few drops of food colouring. You may need to add more water depending on the size of your bottle and length of your straw.
2. Place the bottom of a straw in the bottle so it touches the water. The top of the straw should be sitting well above the mouth of the bottle.
3. Holding the straw in place, tightly seal around the straw and the top of the bottle with plasticine. Be careful not to crush the straw.
4. Blow a little air through the straw into the bottle so that the coloured water to rises up into the straw above the stopper. Be careful when you blow into the straw. If you blow too much air into the bottle a jet of water will squirt back at you.
5. If the water level in the straw drops, it means air is escaping through the seal. You need to make sure you have no leaks in your seal.
6. When there is water in the straw you may need to remove any air bubbles inside the straw by moving a skewer up and down in the straw.

   

   What happens to the water level in the straw?
7. You may need to use an eye-dropper to add water to the straw so the water level is about five centimetres above the top of the bottle.
8. Mark the level of the water in the straw with a pen.
9. You have now calibrated your thermometer to room temperature.
10. Cup your hands around the bottle or place it near something warm in the room. Be careful not to place plastic too close to a heat source or it will melt. What do you notice about the water level in the straw?
11. Place the bottle in the fridge and after about ten minutes take it out and look at the water level in the straw.

What's happening

The thermometer uses the fact that most things expand as they warm up and contract when they cool down.

If you raise the temperature of a gas, the particles that make up the gas absorb heat energy and begin to move faster. This causes the gas to expand.

When the air inside the bottle expands, the pressure inside the bottle increases, pushing down on the liquid inside the bottle and pushing more liquid up the straw. When you cool the air again, it loses energy and decreases the pressure. The coloured water will then be pushed back down the straw by the pressure of the air outside.

A simple bulb thermometer works on a similar principle involving the expansion of liquids.

Standard thermometers use alcohol. Liquid alcohol contracts upon cooling and expands upon heating. Alcohol has a lower freezing point than water, so it will measure temperature below freezing. Adults might have noticed that when some alcohols are stored in the freezer at home they remain a liquid.

A bulb thermometer uses a very small amount of liquid so that it changes temperature quite easily and the tube is extremely small, so slight changes are easily noticed.

Visit The Sky - ROCKET

WARNING:

This activity involves a flying projectile. Make sure you have an adult with you and wear eye protection (safety glasses). Do this activity outside or in a high-ceilinged building like a hall. Never launch with anything breakable above the rocket, especially your face. Never point your canister rocket at anything, except the sky.

What you need

To do this experiment you will need:

• a film canister
• baking soda (sodium bicarbonate)
• vinegar (any kind will work, but white vinegar is easiest to clean up)
• an ice cream stick or teaspoon
• a plate, saucer, tray or similar
• eye protection (glasses, sun glasses or safety goggles)
• an adult.

What to do

1. Take the lid off the film canister. Before adding the ingredients, practise putting on the lid and placing it upside down as described in step 5.
2. Put on your eye protection.
3. Pour a small amount of vinegar, about 5 millimetres deep, into the body of the canister.
4. Using the teaspoon or icecream stick, place enough baking soda to fill the recess in the lid.
5. Hold the body of the canister in one hand and the lid in the other. Quickly and firmly press the lid completely on, place the canister lid down on the plate and stand back. Make sure your plate is on a level surface. Your canister rocket will blast off seconds later. The exact timing will depend on the canister, temperature, amount of ingredients and how tightly you packed the baking soda in.
6. Have a close look at the lid and bubbling ingredients left on the plate.

What's happening?

When vinegar and baking soda mix together, there is a fast chemical reaction. There are several products of the reaction, although it is the carbon dioxide gas (C0₂) that pops the lid off.

As more and more carbon dioxide is produced, the bits of carbon dioxide (called molecules) are squashed together and begin to push, or apply a force, on all the inside surfaces of the canister, including the lid.

Pressure is defined as a force over an area. In this case, it's the force of the carbon dioxide pushing over the inside area of the canister. As the carbon dioxide builds up, so does the pressure inside the canister. The pressure quickly pops the lid off.

A good way to understand what is happening is to take a deep breath in, seal your lips and slowly breathe back out into your mouth. Eventually your mouth cannot hold the pressure and your lips will unseal, letting some air out. Caution: don't overdo this as you can hurt your eardrums.

The carbon dioxide gas pushes down on the lid, although as it is sitting on the plate it can't go anywhere when it pops. The carbon dioxide is also pushing on the inside base of the canister (the top of your rocket) and this pushes it into the air.

Bright View - Electric Lamp

How to Make a Table Lamp

No home can function without light, and nice-looking fixtures don't have to be expensive. With a hardware-store kit and lamp shade, you can turn any large container into a custom-designed table lamp. Tools:

• pliers
• screwdriver
• if required, drill

Materials:

• bottle, jar, or basket for base
• sand or weights
• electric candlestick conversion kit (lamp kit) or socket and cord, plug, threaded hollow rod, and brass sheath
• lamp harp
• lamp shade
• light bulb
• if required, silicone adhesive

Time: 15 minutes to 1/2 hour For the base of the lamp, choose any container you like -- a large wine bottle is ideal, especially the thick, rippled-glass kind or a basketed jug. A large jar, a pottery or ceramic jug, milk can, or a woven wicker basket would also make a good base. The base of the lamp must be firmly weighted. If the container is opaque, fill it with sand or weight it with pieces of brick or lead. If you're using a clear container, you can use anything you like to fill it—seashells, pebbles, buttons, matchbooks, layers of sand, dried beans, or whatever appeals to you. Make sure add have enough weight to keep the lamp base steady. The type of container you use dictates the type of lamp kit, or electric candlestick conversion kit, you should buy. For the easiest wiring job, or for solid containers, buy a kit that simply plugs into the top opening of the container -- choose the standard type or the special kerosene-lamp type. With this kind of kit, the cord is attached at the top of the container, so no drilling is necessary. If you're using a container that isn't solid, such as a wicker basket, buy the lamp components separately: a socket and cord, a plug -- the clip-on type is easiest, a threaded hollow rod -- as long as you want the lamp to be high, a brass sheath to cover it, and a lamp harp. This assembly isn't a kit, but it's almost as easy to put together. With the long rod, the cord runs through the rod to the bottom of the base container; you'll have to drill an opening in the bottom for the cord. If you're using a plug-in lamp kit, weight the lamp base before you wire it. Then, following the manufacturer's instructions, assemble the wiring post. The kit includes several rubber stoppers of various sizes; find the stopper that best fits the top opening of your container. Thread the nipple of the wiring post or rod into the center of the stopper and tighten it securely. Screw the brass washer and locknut onto the base end of the rod; screw the lamp socket onto the other end.

Thread the wiring post through the stopper and plug the stopper in; add a harp and a light bulb.

Insert the assembled wiring post into the weighted container, socket end up, and push the stopper firmly into place. This completes the wiring of the lamp. To attach the lamp shade (select any one you'd like to complement your lamp's base), add a lamp harp, which is a screw-on wire attachment. Attach the harp to the socket base as directed by the manufacturer. Then, remove the locknut at the top of the harp, set the lamp shade into place, and replace the locknut. Finally, screw a light bulb into the socket and plug the lamp in. If you're using a wicker basket and a long threaded rod to wire the lamp, start by drilling a hole in the bottom of the basket for the rod and the cord. If necessary, drill another hole in the basket's cover for the top of the rod to pass through. Drill the holes large enough to accommodate the rod itself on the bottom, and the rod's brass sheath on the top. To assemble the components, thread the plug end of the cord through the rod and pull it through. Secure the socket at the top of the rod with the locking screws provided. Slip the brass sheath over the rod to butt into the socket at the top. Tie a loose knot in the cord near the base of the rod to reduce the stress on the cord. Then set the rod into place in the basket and pull the cord out through the opening in the bottom of the basket. To secure the rod at the lamp bottom, apply a bead of silicone adhesive to it at the bottom of the basket. Set the basket's cover over the rod and secure the rod into the opening with silicone adhesive. To complete the lamp, weight the base as described previously. Be sure to use a weighting material that won't sift out of the basket. Then clip the plug to the end of the cord, as directed by the manufacturer. Complete your lamp by adding a lamp harp, a shade, and a bulb, as directed above. With this lamp now shining brightly, continue to the next page to learn more about creating lamps. You can build one out of stovepipe!

NEED FOR SPEED PRO STREET TRAILOR

LUB DUB LUB DUB - Stethescope

How to MAKE your Stethoscope

1. Cut the neck off a 9” balloon. 2. Stretch the balloon over the mouth of the small plastic funnel making sure that it is tight. 3. Insert the funnel in one end of an 18” section of vinyl tubing. (Tubing can be purchased at home repair stores.) How to USE your Stethoscope The heart is located directly in the center of the chest. However, the lower tip of the heart is closest to the left, front of the chest. Place the tube end of your stethoscope in your ear and place the funnel end over your heart area. Now use your stethoscope to listen to the soft and loud beats (“lub-dub lub-dub” sound) your heart makes! Record how many beats it makes per minute. My Heart Rate = # of Beats__________ in one minute!

HOW IT WORKS

As the heart beats, it causes the stethoscope to vibrate. These vibrations are transmitted as sound to our ears. The soft beat means that the blood is being pumped down into the ventricles and the louder beat means the blood is being pumped up into the arteries.

FUN FACTS:

• Usually, the heart pumps about 4-8 liters of blood per minute. • The heartbeat slows down during sleep and speeds up when we exercise. • Generally a smaller heart beats faster than a larger one. • A child’s heart beats about 100-120 times per minute. • An adult’s heart beats about 70-90 times per minute. • Your heart is about the size of your fist. TRY THIS AT HOME WITH YOUR STETHOSCOPE: • Can you find a beat or pulse anywhere else on your body? • Try to calculate how many times your hearts beat in an hour, a week or a year! • Listen to your heartbeat at rest then exercise for a few minutes, listen again and record the changes.

Spread colours - Spectroscope

What is happening

A spectroscope is a device that separates light into its component colors. The way a spectroscope does this is to make use of something called a diffraction grating. Light reflects and refracts through this diffraction grating, and the different colors of the spectrum all reflect and refract a little differently. This is how the colors are separated into the colors of the rainbow.

A compact disk (CD) contains a large amount of information encoded onto its surface. This information is stored in concentric rings to that it can be read by a laser beam while the disk is spinning. These concentric rings can act as a diffraction grating if the light hits them just right. You see how this works when you build a spectroscope with a CD.

What is needed

• Two 8 1/2 by 11 inch sheets of card stock. This should be light weight cardboard (like the kind used in index cards). Heavy construction paper will also work. If you have a choice of colors for the card stock, darker ones are better.
• 1 compact disk.
• Scotch tape
• Several light sources. During construction a normal flashlight is recommended.

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What to do

Here is a picture of the final spectroscope.

Take one of the sheets of card stock and fold it in half long ways. Cut the sheet of card stock in half along this line. When you have finished you will have two sheets of card stock each one 4 1/4 " by 11". Tape these two sheets together with 3" overlapping long ways. This will give you one long sheet of card stock that is 4 1/4" wide and 19" long. Now take your scissors and cut a notch in this card stock. The notch should be 1/4" wide and 1 1/4" high. Make this notch exactly 1/2 of the distance from either end of the card stock.

Now, take the CD that you have (Fizzy Fuzzy Big and Buzzy by the Refreshments works the best, but please substitute other music according to your own taste) and hold it in your hand by the edges. Look carefully at the side that doesn't have any writing on it. This is the side with all of the encoded information. Tilt the CD back and forth in the light that is in the room. Do you see any rainbows?

While holding the CD with the information/rainbow side up wrap the long card stock around the CD. What you are trying to do is to make a little container like an open coffee can with the card stock as the sides and the CD as the bottom. The notch that you have cut into the card should be at the bottom of the container as shown in the first picture. You are going to use this notch to view the information/rainbow side of the CD. Tape the card stock into the form of a tube that it is now in. Also fasten the CD to the card stock tube with two pieces of tape. Make sure that you are putting the tape on the writing side only. If you put tape on the information side, you may damage the CD.

To finish your spectroscope, cut out a square from you other 8 1/2 by 11" piece of card stock. The square that you cut should be 5 1/2" by 5 1/2". Cut a slit about 2 mm wide and parallel to one of the sides of the square. Center the slit on one of the sides of the square and make it 1/2 inch from the edge (see picture).

The final step in building your CD spectroscope is to place this square directly onto the top of your open tube and CD container. The only thing to be careful of is to make sure that the slit is directly over the notch in the tube. See the first picture. Tape the top onto the tube.

You now have a finished CD spectroscope. The way to use it is to hold a light source up to the slit on the top, and look inside the container through the notch. You should see a very clear strip of rainbow color running from the center hole of the CD to the notch. Move the light source around to see what angle gives the best spectrum.

Try other sources of light. Different light has different color strengths. If you have trouble seeing the spectrum of some specific light, try going into a dark room and having the light you are testing being the only light.

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What is happening

A spectroscope is a device that separates light into its component colors. The way a spectroscope does this is to make use of something called a diffraction grating. Light reflects and refracts through this diffraction grating, and the different colors of the spectrum all reflect and refract a little differently. This is how the colors are separated into the colors of the rainbow.

A compact disk (CD) contains a large amount of information encoded onto its surface. This information is stored in concentric rings to that it can be read by a laser beam while the disk is spinning. These concentric rings can act as a diffraction grating if the light hits them just right. You see how this works when you build a spectroscope with a CD.

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Unseen View - Periscope

Build a Periscope

How to make a periscope? In this section of Science Experiments, you will learn how to build a periscope. You can build a periscope very simply. Follow the following procedures.

Equipment needed to build a periscope

To build a periscope, you need:

• two small, square mirrors
• a piece of strong cardboard 1 foot x 1 foot (30cm x 30cm)
• sticky tape
• ruler
• protractor
• scissors

Method of building periscopes

1. Draw three lines on the cardboard to divide it into four equal strips.
2. Cut squares in two of the strips.
3. Cut two lines on each of the other two strips so they make an angle of 45 degrees with the side of the card.
4. Fold the card into a tube shape and stick it together with tape.
5. Slide the mirrors into the angled slits and tape them in position. One mirror should face upward and the other should face downward.
6. If you hold the periscope sideways, you will be able to see around corners. If you hold it upright, you will be able to see over the heads of people or things that are taller than you are.

How does a periscope work?

A periscope uses two mirrors that bounce reflections between them so people can see around corners or look at things that are too high for them to see. Light from the objects that are out of sight is reflected from the top mirror down into the lower mirror. You are able to see the objects by looking in the lower mirror.

Colourful View - Kaliedascope

Supply List
Mirrors: Three for each kaleidoscope
PVC Pipe: One for each kaleidoscope
PVC End Cap: One for each kaleidoscope
Adhesive-backed Foam Strips: Three pieces for each kaleidoscope
Foam Rope: Three pieces for each kaleidoscope
Petrie Dishes: One for each kaleidoscope
PVC Cement
Transparent Tape: About one roll for every five kaleidoscopes
Labels: With the name of your school or organization
Sharpie Markers: Permanent, in various colors
Small pieces of sandpaper: About 100 grit
Before class: Prepare the materials Cut the acrylic mirror into strips. Vacuum the mirrors. Cut the PVC pipe into 7-7/8 inch tubes. Clean the tubes. Drill holes in the center of the PVC end caps Cut the adhesive-backed foam weather stripping into one-inch pieces. Cut the foam rope into one-inch pieces. Glue the bottoms of the Petrie dishes onto the PVC tubes.
In class: Make the kaleidoscopes
For each kaleidoscope, remove the protective film from the faces of three mirrors.
Gather the mirrors in your hands, long edges together.
Gently and carefully fold the mirrors into a triangle, shiny sides in.
Line up the corners to form an equilateral triangle.
Wind transparent tape around the triangle, approximately 1/2 inch from each end. Students may want to work in pairs for this, one student to hold the mirrors and another student to wind the tape.
When securely and neatly taped, the mirror triangle will not wobble.
Remove the backing from a piece of weather stripping and place it on one side of the triangle, approximately one inch from one end.
Add two more pieces of weather stripping, one to each empty side of the triangle. The three pieces of weather stripping should present a uniform appearance when placed correctly.
Insert the mirrors, weather stripping down, into the PVC tube.
Compress the weather stripping slightly to make it fit.
Insert a one-inch piece of foam cord into the empty place between two points of the triangle.
Insert two more pieces into the remaining spaces in exactly the same manner.
Place the PVC end-cap onto the PVC tube.
The PVC end-cap will fit the tube tightly, so hit the end cap with the flat of your hand to be sure the end-cap is completely on the tube.
Add the self-stick label. Your kaleidoscope has no colors in it, but reflects the world via the mirrors, so we call it a WorldView Kaleidoscope.
Enjoy the view.
To add colors to your kaleidoscope using Sharpie markers
Use the remaining (larger) half of the Petrie dish to create a kaleidoscope with colors. With a few colored Sharpie markers, draw lines on the inside face of the dish. Fewer lines work better than more.
To prevent the world from being seen, lightly sand the outside face of the Petri dish.
To operate the kaleidoscope, hold the colored Petrie dish half onto the end of the kaleidoscope, with the colored side toward the kaleidoscope and the sanded side toward the world, and then rotate the Petrie dish by hand.
Enjoy the view.

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Distant View - Telescope

Physics Experiments /// / /\ | | | | | | /\ (( ( | | | | /\\ .............| |...............| |...0 \\ | | | | \// | | \/ / | | / \/ / (__== ) ) (__ \ __/ ( ( MAKE A BEGINNER'S TELESCOPE A telescope with a tube is nice, but it's more complicated than necessary. A telescope with adjustable focus is useful, but it's hard to build. A project that's too complex and difficult will drive people away, when the goal is to tempt them into building it. Here is an extremely easy version of a Telescope Build-it project. No cardboard tube or adjustable focus mechanism is required. All that you need is a pair of lenses. Tempting? THE LENSES Two lenses are needed to build a telescope. We call these the "objective" lens and the "eyepiece" lens. /\ | | | | /\ (( ( | | | | /\\ .............| |...............| |...0 \\ | | | | \// | | \/ | | | / \/ OBJECTIVE EYEPIECE LENS: LENS: * large * small * weak * powerful * convex only * convex OR concave The "Objective" lens should always be a convex lens. Convex lenses are thicker in the middle, and can be used as magnifying glasses or for concentrating sunlight. Try to find one which is large and weak. The weaker it is, the more powerful your telescope will be. The thinner it is in the center, the weaker it is. _______ _-- --_ <_> Side view of convex lens --_______-- ___----___ _/ \_ /______________\ This type of convex lens also will work The "eyepiece" lens can be either a convex or concave lens. If you use a convex eyepiece, your telescope will turn everything upside-down. This kind of telescope is called a "Newtonian." And if you use a concave lens as your eyepiece, your telescope will not turn things upside-down. This type of scope is called a "Galilean." For your eyepiece, try to find a lens which is small and powerful. A small, powerful magnifying loupe makes a good telescope eyepiece. |\_ _/| | ----_____---- | | _____ | Powerful concave lens. | _---- ----_ | |/ \| _ _ | ---_________--- | | _________ | Weak concave lens. |_--- ---_| You can buy cheap lenses from the suppliers below. USING YOUR TELESCOPE Face a distant, well-lighted object such as a lamp, or distant trees outdoors. Hold your Eyepiece Lens right on your eye and look through it. It's OK to close your other eye. Hold your Objective lens right in front of your eyepiece. Slowly move your Objective lens forward until the scene comes into focus. Sometimes it's hard to find the right distance, so try many different places. Look through your lenses and find the blurry edge of trees or lightbulb, then move the objective lens in or out so that the blurry edge looks sharper. Your lenses are now a telescope! Now that you know the trick, you can make a telescope whenever you find two different lenses lying around. If a friend happens to have two magnifying glasses, grab them, put the more powerful one right on your eye, move the other in and out, and you'll have an instant telescope. HOW TELESCOPES WORK I've read many different explanations of telescopes. Most of them are confusing and complicated. Some are even wrong. So, if you read an explanation and don't understand it, don't blame yourself. Blame the author of the book or encyclopedia for not being a good explainer! Having said this, do I think I can do better? I don't know. A good explanation of a telescope should be easy to understand. I've never seen a really good one, so all I can do is try to explain things in a different way than books usually do, and see how well it works.

MY SIMPLE EXPLANATION: If you put a lens right on your eye, it makes things blurry, but it does not magnify distant scenes. This is how eyeglasses work. They change the blurry-ness or sharpness of what you see, but they don't act as magnifiers when used normally. Now if you move a lens away from your eye, and keep looking through it, everything WILL change size. If the lens is concave (thinner in the center,) everything you see in the lens will get smaller and smaller as you move the lens farther away from your eye. If you use a convex lens instead, everything will get bigger and bigger as you move it away. The convex lens is the interesting one because it makes things bigger when you move it farther from your eye. Keep moving it farther and farther away. You'll find that everything will become VERY big, even infinitely big. And infinitely blurry too. Move the lens a little farther, and things get small again, but now everything seen through the lens is upside-down. By moving the convex lens in and out, we can change the size of everything, or make it all go upside-down or rightside-up. Unfortunately everything is very blurry when you're looking through the lens. If only there was some way to remove the blurryness, we could hold a convex lens in front of our eye and use it to magnify distant scenes. There is a way to remove the blur: wear glasses! Glasses are used to correct blurry vision, and they can fix this blur too. Put another lens right upon your eye. It acts like eyeglasses and makes the image sharp. If you do this, you have constructed a telescope. The objective lens creates a magnified view of distant objects, while the eyepiece lens removes the blur. That's how telescopes work. MAKE A TELESCOPE USING JUST ONE LENS Here's an interesting question. If human beings could focus their eyes better, could we build telescopes with only one lens? Suppose you were able to focus your eyes on an object that was 1/10 inch away from your eye. Couldn't you hold an "objective" lens a few inches away, look through it, then focus really hard with your eyes and create a telescope? The answer is yes! Even if you don't have a superhuman ability to overfocus your eyes, you can still make a simple one-lens telescope. Here's how. Hold a weak convex lens in front of your eye. Close your other eye. Move the lens far away so that everything turns upside-down. Move the lens a bit closer so that everything stays upside-down, but gets bigger and blurry. Now focus your eyes really hard by crossing them. (This might take a bit of practice! Crossing your eyes while one eye is closed is not that easy to do.) The image you see in the lens will become sharper. If it doesn't become completely sharp, then move the lens farther away. Also try moving the lens closer while focusing really, REALLY hard. Everything you see in the lens will be clear, sharp, and magnified! You have made a telescope with nothing but a single lens! Tell your friends about it and they won't believe you. Then show them the trick and they'll be amazed. MAKE A TELESCOPE WITH A LENS AND SOME FOIL It is also possible to make a telescope using aluminum foil and one lens. The lens will act as the telescope's objective lens. To make an eyepiece, we just poke a tiny hole in the foil, and use this pinhole as the telescope eyepiece lens. The tiny hole in the foil removes the blur. But it also makes the image very dim. That's alright, just use this telescope to watch a bright outdoor scene. To make a good pinhole, stack up several layers of aluminum foil, poke the stack with a pin, then separate the layers and choose whichever one has a very round, very small hole. Experiment with different holes; put one on your eye, look through it a brightly-lit scene, and see how sharp everything looks. Smaller holes generally give sharper, dimmer images, but VERY small holes cause blur because of "optical diffraction" effects. You want your pinhole to be very small, but not so small that things become blurry. To make a telescope, hold the best pinhole against your eye and look through it. Look at a brightly lit scene, such as the sunny outdoors outside a classroom window. Now place your objective lens against the pinhole, then move it slowly outwards. When you see a magnified scene, your telescope is working! You can hold your lens in different spots so the scene is either upside down or right side up. An aluminum foil pinhole can be made sturdier by using rubber cement to glue it to a piece of cardboard which has a 1cm hole punched in the center (don't get cement in the tiny pinhole though!) You can use your pinhole-telescope to create a "zoom lens" effect by moving the objective lens towards the pinhole or away. And depending on the distance between the pinhole and the lens, the scene you see can either be upside-down or right-side-up. It's very complicated to build a zoom-lens telescope with real eyepiece lenses, but if you use a pinhole it becomes simple.

MAKE IT EASY - Pin Hole Camera

Making a Pinhole Camera

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An ordinary camera has a lens that makes an image on film. In a pinhole camera. a small hole replaces the lens. You can construct a pinhole camera using:

• corrugated cardboard from a box, or stiff cardboard from the back of a pad of paper
• black paper
• black tape
• a cartridge of 126 film*
• aluminum foil
• two large rubber bands
• a ruler
• a pencil
• scissors
• a sharp knife
• a straight pin or sewing needle

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Making a pinhole camera

The diagram shows the basic construction of a pinhole camera. The body of the camera is a cardboard box that is open at both ends. To make this box, cut a rectangle of cardboard that measures 5 3/4 inches by 2 inches.

Divide the long edge of the rectangle into four equal sections. as shown. Use your knife to score the cardboard along each of the lines. Fold the cardboard along the scores to make an open-ended box.

Before you tape the edges together to make a box, you need to make the interior black to minimize reflection of light within the camera. You can cut a piece of black paper and fold it to make a black lining for your box, or you can cover the inside surface of the cardboard with strips of black tape. You could also paint the inside flat black with spray paint or tempera.

Now tape the edges together to make a box, and tape all the box's edges and corners to prevent light from leaking into the camera.

Insert the box into the film cartridge as shown. It should fit tightly. When you hold the open end of the box up to your eye, you shouldn't see any light leaking in where the box fits into the cartridge.

To make the front of the camera, cut a rectangle of cardboard that measures about 1 3/4 by 3 inches. Cut a square hole that measures about 1/2 inch by 1/2 inch in the center of the rectangle. Line the inside of the front of the box with black paper or tape, leaving the hole open.

Tape a 1-inch square of aluminum foil over the square hole, and make a small pinhole in the center of the foil.

When you aren't taking a picture, you need to cover the pinhole with black paper. We made a shutter that slides into black paper guides. as shown.

To ensure that no light can leak in, tape the box to the front with black tape. Fasten the camera to the cartridge with rubber bands, as shown.

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Taking photos with your pinhole camera

Through the window in the back of the film cartridge, you'll see arrows. Use a coin as shown in the diagram, turning it clockwise to advance the film in the direction of the arrows. Eventually, you'll see the frame number 1 through the window, the first in a series of 1's. Stop advancing the film when the third and fourth 1 in the series are both visible through the window. Now you're ready to take a picture.

To get a sharp photo, it's important to hold your pinhole camera steady To keep the camera steady. one of our staff suggested that you "tape it to a brick." He attached his pinhole camera to a tripod with rubber bands.

This photo was taken with a pinhole camera.