Physics
Assertion (A) : Conductors can be charged by friction.
Reason (R) : Conductors allow charges to flow through them and do not retain static charges.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Static Electricity
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Answer
Assertion is false but reason is true
Explanation
Frictional charging is effective only for insulators. When a conductor is rubbed, any charge produced immediately moves through the material and leaks away to the surroundings (usually to the Earth) unless the conductor is completely insulated. Therefore the Assertion is false.
The Reason correctly states that charges in a conductor are free to move, so a conductor does not easily hold static charge; hence the Reason is true and correctly explains why the Assertion is false.
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Related Questions
Assertion (A) : MCB is more effective than a fuse in household wiring.
Reason (R) : MCB can be reset (raised up) after tripping whereas fuse must be neglected once blown.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Assertion (A) : Lightning is a natural example of static electricity.
Reason (R) : Lightning occurs due to the accumulation of same charges in clouds and earth's surface.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Fill in the blanks:
(a) Like charges …………… while unlike charges …………… .
(b) Mercury is a …………… of electricity while pure water is …………… of electricity.
(c) An ebonite rod when rubbed with fur acquires the …………… charge.
(d) When an uncharged conductor is brought in contact with the disc of a gold leaf electroscope, its leaves …………… .
(e) Charge is shared in charging a conductor by the method of …………… .
Write true or false for each statement:
(a) The number of electrons and protons in an atom are same.
(b) If the charge is not in motion, we call it static electricity.
(c) Human body is a conductor of electricity.
(d) When an ebonite rod is rubbed with fur, the electrons move from ebonite to fur.
(e) When a glass rod is rubbed with dry silk cloth, the electrons move from glass to silk.
(f) The cap of gold leaf electroscope is made of copper.
(g) If a glass rod rubbed with silk is brought near the cap of a negatively charged electroscope, the divergence of leaves will decrease.
(h) In induction, a positively charged body can make an uncharged body positively charged.
(i) A lightning conductor saves the building from lightning.
(j) When a comb is rubbed with dry hair both comb and paper get similarly charged.
(k) A glass rod rubbed with silk repels an ebonite rod rubbed with fur.
(l) When an ebonite rod is rubbed with fur, the protons move from the ebonite rod to the fur.
(m) A conductor has a large number of free electrons.
(n) An ebonite rod can be charged by touching it with a charged copper rod.
(o) To find whether a body is charged or not, an uncharged electroscope is used.
(p) To find whether the charge on a body is positive or negative, an uncharged electroscope is used.
(q) If a negatively charged rod is brought near a negatively charged pith ball electroscope, the pith ball will be stuck with the rod.