A common emitter amplifier has a voltage gain of 50, an input impedance of 100 Ω and an output impedance of 200 Ω. The power gain of the amplifier is:
1. 500
2. 1000
3. 1250
4. 50
A vibration magnetometer placed in a magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2 s in the earth's horizontal magnetic field of 24 T. When a horizontal field of 18 T is produced opposite to the earth's field by placing a current-carrying wire, the new time period of the magnet will be:
1. 1 s
2. 2 s
3. 3 s
4. 4 s
Two positive ions, each carrying a charge \(q\), are separated by a distance \(d\). If \(F\) is the force of repulsion between the ions, the number of electrons missing from each ion will be:
(\(e\) is the charge on an electron)
| 1. | \(\dfrac{4 \pi \varepsilon_{0} F d^{2}}{e^{2}}\) | 2. | \(\sqrt{\dfrac{4 \pi \varepsilon_{0} F e^{2}}{d^{2}}} \) |
| 3. | \(\sqrt{\dfrac{4 \pi \varepsilon_{0} F d^{2}}{e^{2}}}\) | 4. | \(\dfrac{4 \pi \varepsilon_{0} F d^{2}}{q^{2}}\) |
The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be:
1. 2.4 V
2. -1.2 V
3. -2.4 V
4. 1.2 V
A square surface of side \(L\) (metre) in the plane of the paper is placed in a uniform electric field \(E\) (volt/m) acting along the same plane at an angle θ with the horizontal side of the square as shown in the figure. The electric flux linked to the surface in the unit of V-m is:
| 1. | \(EL^{2}\) | 2. | \(EL^{2} cos\theta \) |
| 3. | \(EL^{2} sin\theta \) | 4. | \(0\) |
A series combination of n1 capacitors, each of value C1, is charged by a source of potential difference 4V. When another parallel combination of n2 capacitors, each of value C2, is charged by a source of potential difference V, it has the same (total) energy stored in it, as the first combination has. The value of C2, in terms of C1, is then:
1.
2.
3.
4.
Electromagnets are made of soft iron because soft iron has:
1. low retentivity and high coercive force
2. high retentivity and high coercive force
3. low retentivity and low coercive force
4. high retentivity and low coercive force
| 1. | \(3 \overrightarrow{F}\) | 2. | \(- \overrightarrow{F}\) |
| 3. | \(-3 \overrightarrow{F}\) | 4. | \( \overrightarrow{F}\) |
| Statement I: | Kirchhoff’s junction law follows the conservation of charge. |
| Statement II: | Kirchhoff’s loop law follows the conservation of energy. |
| 1. | Both Statement I and Statement II are incorrect. |
| 2. | Statement I is correct but Statement II is incorrect. |
| 3. | Statement I is incorrect and Statement II is correct. |
| 4. | Both Statement I and Statement II are correct. |
To get an output Y = 1 from the circuit shown below, the input must be:
1. A=0 B=1 C=0
2. A=0 B=0 C=1
3. A=1 B=0 C=1
4. A=1 B=0 C=0
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