Advertisements
Advertisements
Question
When a glass rod is rubbed with a piece of silk cloth the rod ______.
Options
and the cloth both acquire positive charge.
becomes positively charged while the cloth has a negative charge.
and the cloth both acquire negative charge.
becomes negatively charged while the cloth has a positive charge.
Advertisements
Solution
When a glass rod is rubbed with a piece of silk cloth the rod becomes positively charged while the cloth has a negative charge.
Explanation:
When an object is charged by rubbing it against another object, the two objects become oppositely charged. By convention, the charge that the glass rod acquired is positive and the charge that the cloth acquired is negative. Therefore, the rod becomes positively charged, and the cloth becomes negatively charged.
APPEARS IN
RELATED QUESTIONS
A charged glass rod attracts a charged plastic straw.
Select the correct alternative.
Friction is reduced by
State two factors which directly affect the force of friction.
The eraser gets smaller and smaller as you use it more and more. Explain the reason.
Define static friction
Answer the following.
What do you understand by a force?
Answer the following in short.
Define force. Write its SI unit.
Tick the most appropriate answer.
Friction produces
Fill in the blank
Rolling friction is ............. than sliding friction.
Answer the following in short.
How can sliding friction be changed into rolling friction easily?
Answer the following in detail.
Define friction and explain how it is useful to us.
Rolling friction is slightly greater than sliding friction.
Match the following.
| Column I | Column II | |
| a) | Static friction | viscosity |
| b) | Kinetic friction | least friction |
| c) | Rolling friction | objects are in motion |
| d) | Friction between the liquid layers | objects are sliding |
| e) | Sliding friction | objects are at rest |
Complete the analogy.
Knot in a thread : _____ friction : : Ball bearing : _____ friction
Why is a ball bearing used in a cycle hub?
Is there any possibility of making a special device to measure the magnitude of friction directly?

In the following figure, a boy is shown pushing the box from right to left. The force of friction will act on the box
Friction depends on the ______ of two surfaces in contact.
Assertion: Friction always opposes the motion.
Reason: Whenever one surface moves or tries to move over another surface, the force of friction starts acting on the surfaces.
