For a given temperature difference, which of the following pairs will generate maximum thermo e.m.f.
|
(a) Antimony-bismuth |
(b) Silver-gold |
(c) Iron-copper |
(d) Lead-nickel |
(a) Antimony-bismuth
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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 < 
|
Four condensers are joined as shown in the adjoining figure. The capacity of each is 8 μF. The equivalent capacity between the points A and B will be
|
(a) 32 μF |
(b) 2 μF |
(c) 8 μF |
(d) 16 μF |
The plane surface of a plano-convex lens of focal length f is silvered. It will behave as
|
(a) Plane mirror |
(b) Convex mirror of focal length 2 |
|
(c) Concave mirror of focal length f/2 |
(d) None of the above |
An AIR station is broadcasting the waves of wavelength 300 metres. If the radiating power of the transmitter is 10 kW, then the number of photons radiated per second is
|
(a) 1.5 |
(b) 1.5 |
(c) 1.5 |
(d) 1.5 |
Select the correct statement
|
(a) In a full wave rectifier, two diodes work alternately |
|
(b) In a full wave rectifier, two diodes work simultaneously |
|
(c) The efficiency of full wave and half wave rectifiers is same |
|
(d) The full wave rectifier is bi-directional |
