1. When an insulating rod is charged by rubbing, the excess charge generally remains
A.
confined near the region where it was produced
B.
uniformly distributed throughout the Earth
C.
only at the center of the rod
D.
completely absent from the rod
Correct Answer:
confined near the region where it was produced
Explanation:
Charges in an insulator cannot move freely through the material, so the charge usually remains localized near the rubbed region.
2. Why does charge remain localized on the surface of an insulating object?
A.
The charges are unable to move freely through the insulator
B.
The insulator has no atoms
C.
The surface destroys all charges
D.
The charges are converted into heat immediately
Correct Answer:
The charges are unable to move freely through the insulator
Explanation:
In an insulator, electrons are strongly bound to atoms, so excess charge cannot easily spread over the surface.
3. A charged plastic comb is placed near small paper pieces. The charge on the comb is mainly located
A.
on the region where the comb was rubbed
B.
only inside the paper pieces
C.
uniformly throughout the surrounding air
D.
only at the handle, regardless of rubbing
Correct Answer:
on the region where the comb was rubbed
Explanation:
Plastic is an insulator, so the charge produced by rubbing tends to stay near the part of the comb that was rubbed.
4. Which material is most likely to retain charge on the rubbed surface?
A.
Dry plastic
B.
Copper wire
C.
Aluminium sheet
D.
Silver rod
Correct Answer:
Dry plastic
Explanation:
Dry plastic is an insulator, so charge remains localized on its surface instead of moving freely through the material.
5. If one end of a charged insulating rod is touched, the charge on the other end will generally
A.
remain nearly in its original location
B.
move instantly to the touched end
C.
disappear completely from the rod
D.
spread uniformly through the rod immediately
Correct Answer:
remain nearly in its original location
Explanation:
The charge cannot move freely through an insulating rod, so touching one end does not cause rapid charge movement along the rod.
6. The surface charge on a rubbed glass rod is produced mainly by
A.
transfer of electrons during rubbing
B.
creation of new protons on the surface
C.
removal of all atoms from the rod
D.
conversion of light into matter
Correct Answer:
transfer of electrons during rubbing
Explanation:
Rubbing can transfer electrons between materials, leaving an excess or deficit of electrons on the surface of the insulating rod.
7. A charge placed on a dry insulating surface usually
A.
stays close to the point where it is placed
B.
flows immediately to the entire surface
C.
moves only into the surrounding air
D.
changes into a magnetic charge
Correct Answer:
stays close to the point where it is placed
Explanation:
The low mobility of charge carriers in an insulator prevents the charge from spreading easily across its surface.
8. Which condition helps an insulating surface retain its charge for a longer time?
A.
Dry air
B.
Very humid air
C.
Continuous contact with water
D.
A wet surface
Correct Answer:
Dry air
Explanation:
Moisture can provide a path for charge leakage, whereas dry conditions help the surface charge remain localized and retained.
9. When a plastic sheet is rubbed at one corner, the excess charge is initially concentrated
A.
near the rubbed corner
B.
equally at every point on the sheet
C.
only at the center of the sheet
D.
outside the sheet in the air
Correct Answer:
near the rubbed corner
Explanation:
Since plastic is an insulator, the electrons transferred during rubbing remain mainly near the region where rubbing occurred.
10. Compared with a metal surface, charge on an insulating surface is generally
A.
less free to spread over the surface
B.
more free to move throughout the object
C.
always zero after rubbing
D.
unable to attract any nearby object
Correct Answer:
less free to spread over the surface
Explanation:
Charges in an insulator are bound more strongly than in a metal, so surface charge remains localized rather than spreading freely.
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