Explanation:
$\text{impedance}×\cos\theta = \text{resistance}$
$\text{impedance} = \frac{\text{resistance}}{\cos\theta}$
$=\frac{\sqrt{300}}{\frac{\cos\pi}{6}}$
$20\Omega$
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In helium nucleus, there are
|
(a) 2 protons and 2 electrons |
(b) 2 neutrons, 2 protons and 2 electrons |
|
(c) 2 protons and 2 neutrons |
(d) 2 positrons and 2 protons |
A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed 
away, the number of electrons emitted by photo cathode would
|
(a) Decrease by a factor of 2 |
(b) Increase by a factor of 2 |
|
(c) Decrease by a factor of 4 |
(d) Increase by a factor of 4 |
Finger prints are observed by the use of
|
(a) Telescope |
(b) Microscope |
(c) Gallilean telescope |
(d) Concave lens |
Diffraction effects are easier to notice in the case of sound waves than in the case of light waves because
|
(a) Sound waves are longitudinal |
(b) Sound is perceived by the ear |
|
(c) Sound waves are mechanical waves |
(d) Sound waves are of longer wavelength |
The decay constant λ of the radioactive sample is the probability of decay of an atom in unit time, then
|
(a) λ decreases as atoms become older |
|
(b) λ increases as the age of atoms increases |
|
(c) λ is independent of the age |
|
(d) Behaviour of λ with time depends on the nature of the activity |
"Lux" is a unit of
|
(a) Luminous intensity of a source |
(b) Illuminance on a surface |
|
(c) Transmission coefficient of a surface |
(d) Luminous efficiency of source of light |
In an experiment, a graph was plotted of the potential difference V between the terminals of a cell against the circuit current i by varying load rheostat. Internal conductance of the cell is given by
|
(a) xy |
(b) |
(c) |
(d) (x – y) |
