A proton and an α - particle enter a uniform magnetic field perpendicularly with the same speed. If proton takes 25 μ sec to make 5 revolutions, then the periodic time for the α - particle would be
|
(a) 50 μ sec |
(b) 25 μ sec |
(c) 10 μ sec |
(d) 5 μ sec |
(c) 10 μ sec
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The terminal potential difference of a cell when short-circuited is (E = E.M.F. of the cell)
|
(a) E |
(b) E/2 |
(c) Zero |
(d) E/3 |
Two lenses of power 6D and – 2D are combined to form a single lens. The focal length of this lens will be
|
(a) |
(b) |
(c) 4 m |
(d) |
An electric motor operating on a 60 V dc supply draws a current of 10 A. If the efficiency of the motor is 50%, the resistance of its winding is
|
(a) 3Ω |
(b) 6 Ω |
(c) 15 Ω |
(d) 30 Ω |
The capacity of a parallel plate condenser is 10 μF, when the distance between its plates is 8 cm. If the distance between the plates is reduced to 4 cm, then the capacity of this parallel plate condenser will be
|
(a) 5 μF |
(b) 10 μF |
(c) 20 μF |
(d) 40 μF |
