Q. No.A coil is wound of a frame of rectangular cross-section. If the linear dimensions of the frame are doubled and the number of turns per unit length of the coil remains the same, then the self inductance increases by a factor of:
1.
6
2.
12
3.
8
4.
16
| I: | A small magnet takes a longer time in falling into a hollow metallic tube without touching the wall. |
| II: | There is an opposition to motion due to the production of eddy currents in a metallic tube. |
Choose the correct option for the above statements:
| 1. | Both I and II are true and II is the correct explanation for I. |
| 2. | Both I and II are true and II is not the correct explanation for I. |
| 3. | I is true but II is false. |
| 4. | I is false but II is true. |
| 1. | the rectangular, circular, and elliptical loops. |
| 2. | the circular and the elliptical loops. |
| 3. | only the elliptical loop. |
| 4. | any of the four loops. |
A conducting circular loop is placed in a uniform magnetic field of \(0.04\) T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at a rate of \(2\) mm/s. The induced emf in the loop when the radius is \(2\) cm is:
1. \(3.2\pi ~\mu \text{V}\)
2. \(4.8\pi ~\mu\text{V}\)
3. \(0.8\pi ~\mu \text{V}\)
4. \(1.6\pi ~\mu \text{V}\)
A coil of self-inductance \(L\) is connected in series with a bulb \(\mathrm{B}\) and an AC source. The brightness of the bulb decreases when:
| 1. | number of turns in the coil is reduced. |
| 2. | a capacitance of reactance \(X_C = X_L\) is included in the same circuit. |
| 3. | an iron rod is inserted in the coil. |
| 4. | frequency of the AC source is decreased. |
| 1. | \(5\) | 2. | \(10\) |
| 3. | \(15\) | 4. | \(20\) |
The current in a coil varies with time \(t\) as \(I= 3 t^{2} +2t\). If the inductance of coil be \(10\) mH, the value of induced emf at \(t=2~\text{s}\) will be:
1. \(0.14~\text{V}\)
2. \(0.12~\text{V}\)
3. \(0.11~\text{V}\)
4. \(0.13~\text{V}\)
| 1. | \(0.04\) V | 2. | \(0.4\) V |
| 3. | \(4\) V | 4. | \(0.004\) V |
The network shown in figure is a part of a complete circuit. If at a certain instant, the current 'i' is 10 A and is increasing at the rate of A/sec, then is:
| 1. | 6 V | 2. | -6 V |
| 3. | 10 V | 4. | -10 V |
1. \(\frac{3 A_{0} B_{0}}{t}\)
2. \(\frac{4 A_{0} B_{0}}{t}\)
3. \(\frac{3 B_{0}}{A_{0} t}\)
4. \(\frac{4 B_{0}}{A_{0} t}\)
© 2024 GoodEd Technologies Pvt. Ltd.