- A$2\ell_0\sqrt{4\pi\in_0(\ell_0+\text{x})}$
- B$2\text{x}\sqrt{4\pi\in_0\text{k}(\ell_0+\text{x})}$
- C$2(\ell_0+\text{x})\sqrt{4\pi\in_0\text{kx}}$
- D$(\ell_0+\text{x})\sqrt{4\pi\in_0\text{kx}}$
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Source of Sun's energy is
|
(a) Burning of hydrogen |
(b) Fission reactions involving hydrogen |
|
(c) Fusion reactions involving hydrogen |
(d) Some other source |
The internal resistance of a cell of e.m.f. 12V is 5 . It is connected across an unknown resistance. Voltage across the cell, when a current of 60 A is drawn from it, is
|
(a) 15 V |
(b) 12 V |
(c) 9 V |
(d) 6 V |
Assertion : A compass needle when placed on the magnetic north pole of the earth rotates in vertical direction.
Reason : The earth has only horizontal component of its magnetic field at the north poles.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
A proton, a deutron and an a-particle having the same momentum, enters a region of uniform electric field between the parallel plates of a capacitor. The electric field is perpendicular to the initial path of the particles. Then the ratio of deflections suffered by them is

|
(a) 1 : 2 : 8 |
(b) 1 : 2 : 4 |
(c) 1 : 1 : 2 |
(d) None of these |
Two sources of waves are called coherent if
|
(a) Both have the same amplitude of vibrations |
|
(b) Both produce waves of the same wavelength |
|
(c) Both produce waves of the same wavelength having constant phase difference |
|
(d) Both produce waves having the same velocity |
On adjusting the P-N junction diode in forward biased
|
(a) Depletion layer increases |
(b) Resistance increases |
|
(c) Both decreases |
(d) None of these |
Assertion : In transistor common emitter mode as an amplifier is preferred over common base mode.
Reason : In common emitter mode the input signal is connected in series with the voltage applied to the base emitter function.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
What is immaterial for an electric fuse wire
|
(a) Specific resistance of the wire |
(b) Radius of the wire |
|
(c) Length of the wire |
(d) Current flowing through the wire |