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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A radioactive nucleus is being produced at a constant rate a per second. Its decay constant is l. If N0 are the number of nuclei at time t = 0, then maximum number of nuclei possible are
|
(a) |
(b) |
(c) N0 |
(d) |
If the half life of a radioactive sample is 10 hours, its mean life is
|
(a) 14.4 hours |
(b) 7.2 hours |
(c) 20 hours |
(d) 6.93 hours |
Boron rods in nuclear reactor are used as a
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(a) Moderator |
(b) Control rods |
(c) Coolants |
(d) Protective shield |
Two unlike charges of magnitude q are separated by a distance 2d. The potential at a point midway between them is
|
(a) Zero |
(b) |
(c) |
(d) |
A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be
|
(a) Halved |
(b) The same |
(c) Doubled |
(d) Quadrupled |
Two bulbs are working in parallel order. Bulb A is brighter than bulb B. If 
and 
are their resistance respectively then
|
(a) |
(b) |
(c) |
(d) None of these |
1A current flows through an infinitely long straight wire. The magnetic field produced at a point 1 metres away from it is
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(a) 2 |
(b) |
(c) 2 |
(d) 2π |
