The current through choke coil increases form zero to 6A in 0.3 seconds and an induced e.m.f. of 30 V is produced. The inductance of the coil of choke is
|
(a) 5 H |
(b) 2.5 H |
(c) 1.5 H |
(d) 2 H |
(c) 1.5 H
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The electric bulbs have tungsten filaments of same length. If one of them gives 60 watt and other 100 watt, then
|
(a) 100 watt bulb has thicker filament |
|
(b) 60 watt bulb has thicker filament |
|
(c) Both filaments are of same thickness |
|
(d) It is possible to get different wattage unless the lengths are different |
X-rays are produced in X-ray tube operating at a given accelerating voltage. The wavelength of the continuous X-rays has values from
| (a) 0 to ∞ |
(b)  to ∞, where 
|
(c) 0 to  where
|
(d) to , where 0 < 
|
CO2 gas is found in which of the following pairs of the planet
|
(a) Earth and Mercury |
(b) Mercury and Saturn |
|
(c) Venus and Saturn |
(d) Venus and Mars |
The resistance of an incandescent lamp is
|
(a) Greater when switched off |
|
(b) Smaller when switched on |
|
(c) Greater when switched on |
|
(d) The same whether it is switched off or switched on |
Four plates of the same area of cross-section are joined as shown in the figure. The distance between each plate is d. The equivalent capacity across A and B will be
|
(a) |
(b) |
(c) |
(d) |
In a discharge tube at 0.02 mm, there is a formation of
|
(a) FDS |
(b) CDS |
(c) Both space |
(d) None of these |
A fish is a little away below the surface of a lake. If the critical angle is 49°, then the fish could see things above the water surface within an angular range of θ° where
|
(a) θ = 49° |
(b) θ = 90° |
(c) θ = 98° |
(d) θ = 24 |
