Q. No.
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.
An aeroplane in which the distance between the tips of wings is 50 m is flying horizontally with a speed of 360 km/hr over a place where the vertical component of earth magnetic field is . The potential difference between the tips of wings would be:
| 1. | 0.1 V | 2. | 1.0 V |
| 3. | 0.2 V | 4. | 0.01 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. |
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. \(\frac{3 A_{0} B_{0}}{t}\)
2. \(\frac{4 A_{0} B_{0}}{t}\)
3. \(\frac{3 B_{0}}{A_{0} t}\)
4. \(\frac{4 B_{0}}{A_{0} t}\)
An electric potential difference will be induced between the ends of the conductor shown in the diagram when the conductor moves in the direction of:
1. \(P\)
2. \(Q\)
3. \(L\)
4. \(M\)
The number of turns in a coil of wire of fixed radius & length is 600 and its self-inductance is 108 mH. The self-inductance of a coil of 500 turns will be:
1. 74 mH
2. 75 mH
3. 76 mH
4. 77 mH
A magnetic rod is inside a coil of wire which is connected to an ammeter. If the rod is stationary, which of the following statements is true?
| 1. | The rod induces a small current. |
| 2. | The rod loses its magnetic field. |
| 3. | There is no induced current. |
| 4. | None of these. |
A coil of resistance 20 and inductance 5 H has been connected to a 200 V battery. The maximum energy stored in the coil is:
| 1. | 250 J | 2. | 125 J |
| 3. | 500 J | 4. | 100 J |
An aluminium ring \(B\) faces an electromagnet \(A\). If the current \(I\) through \(A\) can be altered, then:
| 1. | whether \(I\) increases or decreases, \(B\) will not experience any force. |
| 2. | if \(I\) decreases, \(A\) will repel \(B\). |
| 3. | if \(I\) increases, \(A\) will attract \(B\). |
| 4. | if \(I\) increases, \(A\) will repel \(B\). |
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