Electrostatics test

1.      Static electricity is caused when two objects rub together.

a)      Should the objects be good conductors or good insulators ?           .............................

b)      Explain why

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2.   A piece of plastic is rubbed with a cloth. The cloth becomes negatively charged. This is because (tick correct one)

    A    Protons move from the plastic to the cloth

    B    Electrons move from the plastic to the cloth

    C    Protons move from the cloth to the plastic

    D    Electrons move from the cloth to the plastic

3.      Sound travels at 340 m/s in air.

a)      If you hear thunder 8 seconds after you see lightning how far away is the lightning ?

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b)      What assumption did you have to make for this calculation ?

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4.      True or false ?

       Like charges attract, unlike charges repel                                                          

       When polythene is rubbed with wool, positive charges move from the polythene to the wool

      Metal water pipes in the home can be used as an electrical earth

       The tip of a lightning conductor should have a sharp point

       It could be dangerous to fly a kite in thundery weather

       Blobs of solder on electrical equipment should be rounded rather than pointed

       A conductor is a material that allows the easy movement of protons

       In electrolysis positive copper ions are deposited at the cathode

       Electrolysis is more effective when an alternating current is used

       The anode attracts negative atoms

5.   Figure 1 shows a small ball, C,  which is positively charged. It is hung on a long insulating thread.

Figure 2 shows what  happens when a charged plastic strip, A, is brought towards the ball.

Figure 3 shows what happens when a different plastic strip, B is brought towards the ball.

a)      What does this experiment tell us about:

i.                     the charge on A?............................................................................................................

[1]

ii.                   the charge on B?............................................................................................................

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[2]

b)      Explain why the ball must be hung from an insulating thread in this experiment.

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[2]

c)      How could A and B have been charged?

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