Oh, no! That man's just been electrocuted by a lemon! Heh, heh! I was just joking, of course, but have you ever wondered how people get all that electricity into a little battery? Amazing, isn't it? Well, you can get electricity from a lemon too! This is what you'll need...
A lemon (of course!)
A galvanised steel nail
Plastic-coated wire
Copper wire
A compass
1. Press the lemon hard on the table so that it's juicy inside.
2. Get an adult to help you to strip the ends of the plastic-coated wire.
3. Twist one of the bared ends of the wire around the copper wire. Push the copper wire into the lemon.
4. Wrap part of the wire around the compass. Wind the other bare end of the wire around the galvanised nail. Push the nail into the lemon. Does the needle of the compass move?
THE WHYS AND WHEREFORES
Electricity, put simply, is the movement of tiny particles called electrons. A battery has to have three parts: a source of electrons, a place for the electrons to go, and something to carry the electrons from one place to the other. In the lemon battery, the iron nail gives out electrons, which move along the insulated wire to the copper wire. Since electricity has a magnetic field, it causes the compass' needle to move.
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Anonymous2013-10-16 2:24
WATER GLUE
What do you use when you want to stick things together ? Water, of course! You're probably shaking your head, saying that can't be. Did you know, however that water's pretty sticky, too. Try this trick out and see for yourself.
You'll need...
A glass of water
Some stiff cardboard
Some weights such as buttons or coins.
1. Cut the cardboard so that you get a strip with a circle at the end.
2. Make two right-angled folds in the cardboard. One where the circle joins the strip and the other about two inches away from the first. It is very important that you get good clean folds.
3. Now, balance the whole thing on the rim of an empty glass.
4. Place a button or a small coin on the end of the card. What happens?
5. Replace the cardboard strip. But this time, fill the glass with water till it just touches the bottom of the circle.
6. Put weights on the end of the cardboard. What happens?
THE WHYS AND WHEREFORES
Water and other liquids have a property called 'adhesion'. This means they will 'stick' to other substances. Water 'sticks' to the cardboard circle because of this and helps to support the weights at the other end. You'll be surprised how much weight 'adhesion' can support.
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Anonymous2013-10-17 4:14
THUNDER PAPER
KABOOM! What was that? Thunder? No, it's just paper. This is a great trick to play on your friends - scare them with paper! This interesting trick will make your friends jump - right out of their skins!
You'll need...
A sheet of paper about 30cm x 40cm
1. Fold the long edges of the paper together and open it again.
2. Next fold down each of the corners to the first centre fold.
3. Fold the paper in half.
4. Fold the paper in half again, and then open it out.
5. Now, fold down the top two corners.
6. Fold the paper back to make a triangle, and you're all set to startle.
7. Grip the banger firmly by the top two corners. Snap it down sharply with a quick flick of your wrist. KABOOM!
THE WHYS AND WHEREFORES
When you snap the banger down, the flap of paper springs out, causing a sudden movement of air. This sends a powerful sound wave rushing through the air. You hear this as a bang. A number of loud noises, such as thunder, occur because of this. When lightning flashes, it heats up the air and causes it to expand very quickly. Thunder is the 'bang' that you hear!
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Anonymous2013-12-25 10:59
PINHOLE CAMERA
You'll need...
Aluminium foil
Tracing or
other thin paper
A shoebox
A piece of dark cloth
A pin
1. Cut a square about 5 cm by 5 cm in one end of the shoebox and cover it with aluminium foil.
2. Cut a square at the other end of the box and cover that with the tracing paper. Cover this end with the dark cloth.
3. Tape up the box. Make sure there are no cracks through which light can enter the box.
4. Prick a tiny hole in the aluminium foil. This is your pinhole lens.
5. Point your 'camera' at a brightly lit object. Look at the tracing paper underneath the dark cloth. You should see an upside down image of the object.
THE WHYS AND WHEREFORES
A hole that's small enough behaves like a lens. The pinhole acts as a lens and focuses light onto the screen at the back of the box. The image you get will be upside down. (If you're shortsighted, try looking through a pinhole without your glasses. What do you see?)
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Anonymous2013-12-25 11:39
PERISCOPE
You can run, but you can't hide, because I'll always be able to find you with my Super-Special X-Ray Vision Periscope! All right, maybe it's not that powerful, but would you like to be able to look over walls and round corners? Well, let me show how you can do that. It's how people in submarines see above the surface of the sea.
You'll need...
Four strips of stiff dark-coloured card 30 cm x 7 cm
Two small mirrors about 8 cm x 7 cm
1. Cut a square, 5 cm by 5 cm about 1 cm from the end of two cards.
2. Draw a straight line 7 cm from each end of the remaining cards. Check with the diagram. Then draw diagonal lines like those in the picture.
6. Push the mirrors into the slots and hold them there with sticky tape.
7. Cover the ends of the box with black paper and you're all ready to bend light.
THE WHYS AND WHEREFORES
As you know, light travels in straight lines (that's why you can't see around corners). If you look at a mirror from the right, you won't be able to see your reflection, only that of things to your left. This is because mirrors reflect light in a fixed manner. We take advantage of this fact in a periscope. By placing mirrors in the correct positions, we can, in a way, see around corners.