WW3 Static Electricity

Electrical forces ____.

• can cause objects to only attract each other

• can cause objects to only repel each other

• can cause objects to attract or repel each other

• have no effect on objects

Upon entering the room, you observe two balloons suspended from the ceiling. You notice that instead of hanging straight down vertically, the balloons seems to be repelling each other. You can conclusively say ...

• both balloons have a negative charge.

• both balloons have a positive charge.

• one balloon is charge positively and the other negatively.

• both balloons are charged with the same type of charge.

Balloons X , Y and Z are suspended from strings as shown at the right. Negatively charged balloon X attracts balloon Y and balloon Y attracts balloon Z. Balloon Z ____.

• may be positively charged, negatively charged or neutral

• must be positively charged

• must be negatively charged

• must be neutral

One of these isolated charged spheres is copper and the other is rubber. The diagram below depicts the distribution of excess negative charge over the surface of two spheres. Which copper and which is rubber?

• A is copper, B is rubber

• A is rubber, B is copper

A rubber balloon possesses a positive charge. If brought near and touched to the door of a wooden cabinet, it sticks to the door. This does not occur with an uncharged balloon. These two observations can lead one to conclude that the wall is _____.

• electrically neutral

• negatively charged

• a conductor

• lacking electrons

Which of the diagrams below best represents the charge distribution on a metal sphere when a positively charged plastic tube is placed nearby?

• A

• B

• C

• D

During a physics lab, a plastic strip was rubbed with cotton and became positively charged. The correct explanation for why the plastic strip becomes positively charged is that ...

• the plastic strip acquired extra protons from the cotton.

• the plastic strip acquired extra protons during the charging process.

• protons were created as the result of the charging process.

• the plastic strip lost electrons to the cotton during the charging process.

Which statement best explains why a rubber rod becomes negatively charged when rubbed with fur?

• The rubber that the rod is made of is a better insulator than fur.

• The fur is a better insulator than the rubber.

• Molecules in the rubber rod have a stronger attraction for electrons than the molecules in the fur.

• Molecules in the fur have a stronger attraction for electrons than the molecules in the rubber rod.

Two neutral conducting pop cans are touching each other. A positively charged balloon is brought near one of the cans as shown below. The cans are separated while the balloon is nearby, as shown. After the balloon is removed the cans are brought back together. When touching again, can X is ____.

• positively charged

• negatively charged

• neutral

• impossible to tell

A positively charged balloon is brought near a neutral conducting sphere as shown below. While the balloon is near, the sphere is touched (grounded). Electrons move ____ .

• into the sphere from the ground (hand)

• out of the sphere into the ground (hand)

• into the sphere from the balloon

• out of the sphere into the balloon