- AAtomic distances (=10-11m)
- BNuclear distances (=10-15m)
- CCharged as well as uncharged particles
- DAll the distances
Explanation:
Coulomb's law is true for all distances whether it is small and large. Hence it is called a long range force.
Coulomb's force $\text{F}=\frac{\text{q}_1\text{q}_2}{4\pi\in_\circ\text{r}^2}$
$\Rightarrow\text{F}\propto\frac{1}{\text{r}^2}$
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A varying current in a coil changes from 10 amp to zero in 0.5 sec. If average EMF is induced in the coil is 220 volts, the self inductance of coil is
|
(a) 5 H |
(b) 10 H |
(c) 11 H |
(d) 12 H |
The electrical circuits used to get smooth d.c. output from a rectifier circuit is called
|
(a) Filter |
(b) Amplifier |
(c) Full wave rectifier |
(d) Oscillator |

A bar magnet is held perpendicular to a uniform magnetic field. If the couple acting on the magnet is to be halved by rotating it, then the angle by which it is to be rotated is
|
(a) 30o |
(b) 45o |
(c) 60o |
(d) 90o |
A radioactive substance has an average life of 5 hours. In a time of 5 hours
|
(a) Half of the active nuclei decay |
(b) Less than half of the active nuclei decay |
|
(c) More than half of the active nuclei decay |
(d) All active nuclei decay |
A rectangular coil of 300 turns has an average area of average area of 25 cm × 10 cm. The coil rotates with a speed of 50 cps in a uniform magnetic field of strength 4
about an axis perpendicular of the field. The peak value of the induced e.m.f. is (in volt)
|
(a) 3000 π |
(b) 300 π |
(c) 30 π |
(d) 3 π |