Five balls numbered 1 to 5 are suspended using separate threads. Pairs (1, 2), (2, 4) and (4, 1) show electrostatic attraction, while pair (2, 3) and (4, 5) show repulsion. Therefore ball 1 must be
|
(a) Positively charged |
(b) Negatively charged |
(c) Neutral |
(d) Made of metal |
(c) Neutral
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The net resistance of a voltmeter should be large to ensure that
|
(a) It does not get overheated |
|
(b) It does not draw excessive current |
|
(c) It can measure large potential difference |
|
(d) It does not appreciably change the potential difference to be measured |
A sensitive magnetic instrument can be shielded very effectively from outside magnetic fields by placing it inside a box of
|
(a) Teak wood |
(b) Plastic material |
|
(c) Soft iron of high permeability |
(d) A metal of high conductivity |
Vibration magnetometer works on the principle of
| (a) Torque acting on the bar magnet |
| (b) Force acting on the bar magnet |
| (c) Both the force and the torque acting on the bar magnet |
| (d) None of these |
Antimony and bismuth are usually used in a thermocouple, because
|
(a) Negative thermal e.m.f. produced |
(b) Constant thermal e.m.f. produced |
|
(c) Lower thermal e.m.f. produced |
(d) Higher thermal e.m.f. produced |
Assertion : Electric lines of force cross each other.
Reason : Electric field at a point superimpose to give one resultant electric field.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If assertion is false but reason is true. |
