A thick wire is stretched so that its length become two times. Assuming that there is no change in its density, then what is the ratio of change in resistance of wire to the initial resistance of wire
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(a) 2 : 1 |
(b) 4 : 1 |
(c) 3 : 1 |
(d) 1 : 4 |
(c) 3 : 1
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The capacity of a parallel plate capacitor with no dielectric substance but with a separation of 0.4 cm is 2 μF. The separation is reduced to half and it is filled with a dielectric substance of value 2.8. The final capacity of the capacitor is
|
(a) 11.2 μF |
(b) 15.6 μF |
(c) 19.2 μF |
(d) 22. 4 μF |
A potential difference of 2V is applied between the opposite faces of a Ge crystal plate of area 1 cm2 and thickness 0.5 mm. If the concentration of electrons in Ge is 2 × 1019/m3 and mobilities of electrons and holes are 0.36 
and 0.14 respectively, then the current flowing through the plate will be
|
(a) 0.25 A |
(b) 0.45 A |
(c) 0.56 A |
(d) 0.64 A |
Two identical short bar magnets, each having magnetic moment M, are placed a distance of 2d apart with axes perpendicular to each other in a horizontal plane. The magnetic induction at a point midway between them is
|
(a) |
(b) |
(c) |
(d) |
Masses of three wires of copper are in the ratio of 1 : 3 : 5 and their lengths are in the ratio of 5 : 3 : 1. The ratio of their electrical resistances are
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(a) 1 : 3 : 5 |
(b) 5 : 3 : 1 |
(c) 1 : 15 : 125 |
(d) 125 : 15 : 1 |
The maximum efficiency of full wave rectifier is
|
(a) 100% |
(b) 25.20% |
(c) 40.2% |
(d) 81.2% |
Which of the following gates will have an output of 1
|
(a)
(a)
|
(b)
|
(c)
|
(d)
|
