Explanation:
A potentiometer has very large resistance. To read load voltage or voltage across any circuit element, potentiometer is connected parallel across it. Thus, the load voltage or circuit voltage gets applied across the potentiometer but as the resistance is very high compared to load resistance, you can safely assume their is almost no current flowing through potentiometer. As power = VI, the power loss in potentiometer is almost equal to zero as current through it remains zero.
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A rocket is going away from the earth at a speed of 106 m/s If the wavelength of the light wave emitted by it be 5700 Å, what will be its Doppler's shift
|
(a) 200 Å |
(b) 19 Å |
(c) 20 Å |
(d) 0.2 Å |
A person wears glasses of power – 2.0 D. The defect of the eye and the far point of the person without the glasses will be
|
(a) Nearsighted, 50 cm |
(b) Farsighted, 50 cm |
(c) Nearsighted, 250 cm |
(d) Astigmatism, 50 cm |
The S.I. unit of radioactivity is
|
(a) Roentgen |
(b) Rutherford |
(c) Curie |
(d) Becqueral |
The maximum illumination on a screen at a distance of 2 m from a lamp is 25 lux. The value of total luminous flux emitted by the lamp is
|
(a) 1256 lumen |
(b) 1600 lumen |
(c) 100 candela |
(d) 400 lumen |