   A sheet of paper and a pencil may be useful.

 Support easyphysics.net by visiting our advertisers' websites. Chapter 12 Quiz

1. Calculate the net charge on a material consisting of
 a) 7 x 1010 electrons ( e.g. "1.00*10^-10 C" ) b) 7 x 1013 electrons and 8 x 1011 protons. ( e.g. "1.00*10^-10 C" )

2. What happen if two identical charges are close together?
( e.g. "a" )

 a) attract each other b) repel each other c) nothing happens. d) it depends on presense of air.

3. What is electric field lines for two proton and one electron?
( e.g. "a" )

 a) b) c) d) 4. What would the mass of a proton be if the gravitational and electric forces between a pair of protons were the same?
( e.g. "1.00*10^-10 kg" )

5. There are two balls that weigh 50 g. Ball A is fixed at a bar and the other ball B is underneath the ball A. They have identical q but have opposite charges. The ball B is 50 cm from ball A. What is the charges of ball A and B if ball B is at rest? ( e.g. "1.00*10^-10 C")

6. A small ball contains about 2.5*1030 protons and similar number of electrons. Suppose there are two of these balls, and they are 10 m apart and 0.2 % of the electrons on one ball is transferred to the other. How much force is required to hold the two balls apart at this distance? ( e.g. "1.0*10^10 N" )

7. There are two identical blocks and each one weigh 500 g, but they have opposit charge. If the coefficient static friction of block between floor is 0.30 and distance between two blocks is 70 cm. What is the minimum charge that make the block move? ( e.g. "1.00*10^-10 C" )

8. Which one of these has the highest potential energy?
( e.g. "a" )

 a) b) c) d) 