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EXPERIMENT I -- experiment was performed in school meeting
Materials:
Two electric wires (~1 ft each), three 1.5 V batteries, one small
light bulb (4.5 V), two copper plates, water in a container, and some table salt.
Procedure:
Line up the three batteries in a way similar to a flashlight, use
tape to hold them together. Connect one end of each electric wire to a copper
plate. Tire the metal part around the light bulb with the other end of an
electric wire. Attach the open end of the 2nd electric wire to the bottom of
the battery set. Put the metal base of the light bulb on the + end of the
battery set. Put the two copper plates into water while keeping them apart.
Observation:
the light bulb does not light up. Now put some table salt into water and slowly stir to dissolve the salt.
Observation:
A dim light starts to appear and becomes brighter as you mix
the salt water.
Question #1:
Why does table salt turn water into an electric conductor?
Question #2:
What will happen if you put sugar instead of salt into the
water? You may try this yourself to find out.
EXPERIMENT II
Fill a large balloon with some pieces of dry ice through a funnel. (Remember to
wear gloves). You can even add some warm water to the balloon. Tie the
balloon and hang it on a scale, record the weight as it expands. You
will see the balloon expand as if it is blowing itself up. However, the weight of
the balloon appears to decrease as it gets bigger. If you put enough dry ice in
the balloon, the balloon will bust. This is supposed to happen, BUT DO BE
CAREFUL. Stand far away from the balloon when it is about to pop.
Question #1:
Why does the balloon blow itself up?
Question #2:
Why does the balloon become lighter as it turns bigger and
bigger?
Hint: We assume no gas escaping from the balloon.
Please sent your answers and/or questions to
*** Guojie Ho at jskho2001@yahoo.com (978)443-9733 or
*** David Block at dblock@theworld.com (978)440-8858
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