PHYSICS ELECTRIC CHARGES

用戶83707

2010-12-24 2:57 am

1. State whether following statements are correct or not and EXPLAIN.

a) WHen a neutral object is attracted by a charged object, the electric force on the neutral object must be greater than that on the charged object.

b) When a charged conductor is brought close to a neutral object, the charge distribution on the conductor will change

2. If a charged copper rod is brought close to some Aluminium scraps, which of the following situations is impossible? EXPLAIN

A. The scraps will be attracted to the rod and stick on it.
B, THe scraps will be attracted to the rod and then repelled after touching it.
C. the scraps will be repelled by rod.
D. the scraps will remain at rest,

3. A neutral conductor is placed on the ground. Which of the followng will give it a net negative charge?

(1) Touch it with a negatively charged conductor.
(2) Bring a positively charged conductor near it without touching it.
(3) Place it on an insulating stand and connect it to the neagtive terminal of an EHT supply.

A. (1)
B. (2)
C. (1) and (3)
D. (2) and (3)

REMEMBER TO EXPLAIN THANK YOU VERYMUCH !!!

回答 (1)

天同

2010-12-24 4:03 am

✔ 最佳答案

1. (a) Wrong. The two forces are equal because they are an action-reaction pair.
(b) Correct. The electric field from the charged conductor causes electrons in the neutral object to move, hence charge re-distribution occurs.

2. Option CThe induced charges on the aluminium scrap are always opposite in sign to the charges on the copper rod. Hence, in no circumstance should repulsion occur.

3. Option DThe method described in statement (1) cannot be used because the neutral conductor is placed on groun, touching it with a charged conductor will conduct away all the charges.

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