1 Curie is equal to
|
(a) 3 |
(b) 3.7 |
|
(c) 5 |
(d) 3.7 |
1 Curie is equal to
|
(a) 3 |
(b) 3.7 |
|
(c) 5 |
(d) 3.7 |
(d) 3.7
disintegrations/sec
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The resistance of a 5 cm long wire is 10 W. It is uniformly stretched so that its length becomes 20 cm. The resistance of the wire is
|
(a) 160 W |
(b) 80 W |
(c) 40 W |
(d) 20 W |
The magnetic induction at a point P which is distant 4 cm from a long current carrying wire is . The field of induction at a distance 12 cm from the same current would be
|
(a) 3.33 |
(b) 1.11 |
(c) 3 |
(d) 9 |
In optical instruments, the lenses are used to form images by:
$1:1$
$1:2$
$\pi:2$
$2:\pi$

When the distance between the charged particles is halved, the force between them becomes
|
(a) One-fourth |
(b) Half |
(c) Double |
(d) Four times |
A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be
| (a) A P-type semiconductor | (b) An N-type semiconductor |
| (c) A PN-junction | (d) An intrinsic semiconductor |
When phosphorus and antimony are mixed in zermaniun, then
|
(a) P-type semiconductor is formed |
(b) N-type semiconductor is formed |
|
(c) Both (a) and (b) |
(d) None of these |