STATTIC ELECTRICITY-FORMATIVE ASSESSMENT

Which of these materials is an electrical conductor 

• Paper

• plastic

• silver

• wood

Answer explanation

All metals are good conductors. The only metal in the list is silver

A polythene rod repels an inflated balloon hanging from a nylon thread. 

Why do the rod and balloon repel? 

• The rod and the balloon have opposite charges.

• The balloon is charged but the rod is not.

• The rod is charged but the balloon is not. 

• The rod and the balloon have like charges.

Answer explanation

the law of electrostatics states that : like charges repel and unlike charges attract

Two plastic rods P and Q are both negatively charged. Rod P hangs freely.  The end of rod Q is brought near to end X of rod P, and then near to end Y of rod P.  What happens to the rods in each position?  

• Near end x, they will attract and near end Y, they will attract

• Near end x, they will attract and near end Y, they will repel

• Near end x, they will repel and near end Y, they will attract

• Near end x, they will repel and near end Y, they will repel

Answer explanation

since they are all charged negatively, like charges repel

Two balloons, X and Y, are suspended by insulating threads. They are each held near a negatively charged balloon. The balloons hang as shown.

What is the charge on balloon X and what is the charge on balloon Y?

• Balloon X and Y are both negative

• Balloon X is negative while Y is positive

• Balloon X is Positive while Y is Negative

• They are both positive

A student did an experiment with two strips of polythene. She held the strips together at one end. She rubbed down one strip with a dry cloth. Then she rubbed down the other strip with the dry cloth. Still holding the top ends together, she held up the strips.

What movement would you expect to see? 

• the bottom will move apart

• the bottom will move closer 

A student did an experiment with two strips of polythene. She held the strips together at one end. She rubbed down one strip with a dry cloth. Then she rubbed down the other strip with the dry cloth. Still holding the top ends together, she held up the strips.

During rubbing , .................................. are transferred from the ........................ to the ............................

The cloth is left with a ................... charge. Each strip has a negative charge hence they ..........................

• A

• B

• C

• D

• A

• B

• C

• D

• A

• B

• C

• D

• Q

• R

• S

• T