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Friday, 23 August 2013

How much noise can produce paper cup?



How much noise can produce paper cup?
 
How much noise can produce paper cup

materials needed

plastic cup (or paper)
string, about 30 cm (12 in.) long
Half of a toothpick

Procedure

1. Make a small hole in the bottom of the cup, at the center. You can use the toothpick or your pencil to make the hole.
2. Insert the end of the string through the hole in the cup.
3. Tie the string around the half toothpick, so the toothpick will be on the outside of the cup.
4. Hold the cup in one hand. Squeeze the string with the thumb and index finger of the other hand, and pull, holding the string tight, but allowing it to slip through your fingers.
5. Did you hear anything? If not, squeeze a little tighter next time.
6. Wet the string with water and do it again.
7. What happened? Explain, and have fun!

                For problem solvers:

 Experiment with different materials. The variables are the cup, the string, the water, and how tightly you held the string with your fingers. Change one variable at a time and see what differences you can make. Predict what differences each change will make before you try it.
                if you can find a small feather or two and some rally eyes, you could decorate this noisemaker and call it the yellow chicken, the red hen, or something like that. you decide. you could fashion a beak out of a clothespin or some other suitable object.
                why does this thing make sound? what is the role of the cup?

Experiment with Short Circuit



What is a short circuit? 

Short circuit is an electrical circuit that allows a current to travel along an unintended path, often where essentially no (or a very low) electrical impedance is encountered. The electrical opposite of a short circuit is an "open circuit", which is an infinite resistance between two nodes. It is common to misuse "short circuit" to describe any electrical malfunction, regardless of the actual problem Source: Wikipedia

Experiment with Short Circuit

Do Experiment

Materials needed
·         one 1.5-volt flashlight battery 
·         Two 25 cm ( 10 in.) lengths of single strand insulated copper wire of 20 or 22 gauge.
·         small light socket with flashlight bulb
·         small screw driver 

One 25 cm (10-in) length of copper wire, similar to that used in activity 8.2, stripped on both ends. 

Procedure
1.      Connect your circuit so there is a complete path and the light turns on.
2. Strip (clean off) the insulation from 1 cm (1/2 in.) in the centre of each wire. Does the light still go on?
3. Put the bare ends of the extra piece of wire across the bare sections of your circuit wires. Does the light go one?
4. What do you think has happened? Why?
5. Feel the ends where the bare ends are touching. Do you notice anything?
6. You have made a short circuit. Discuss with your teacher and the other class members what that means.
2.       

Conclusion:


Share us your results with us.

Caution:
do not leave the circuit connected this way for more than a few seconds. If the battery is strong the wire might become hot enough to burn fingers, though it will still not cause an electrical shock. It will also run thee battery down very rapidly



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