Q. No.A metallic ring is attached to the wall of a room. When the north pole of a magnet is brought near to it, the induced current in the ring will be:
| 1. | first clockwise and then anticlockwise. |
| 2. | in the clockwise direction. |
| 3. | in the anticlockwise direction. |
| 4. | first anticlockwise and then clockwise. |
An electron moves on a straight-line path \(XY\) as shown. The \(abcd\) is a coil adjacent to the path of the electron. What will be the direction of the current, if any induced in the coil?
| 1. | \(abcd\) |
| 2. | \(adcb\) |
| 3. | The current will reverse its direction as the electron goes past the coil. |
| 4. | No current is induced. |
| 1. | \(BA\) and \(CD\) | 2. | \(AB\) and \(CD\) |
| 3. | \(BA\) and \(DC\) | 4. | \(AB\) and \(DC\) |
| 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. |
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 \(B\). |
The radius of a loop as shown in the figure is \(10~\text{cm}.\) If the magnetic field is uniform and has a value \(10^{-2}~ \text{T},\) then the flux through the loop will be:
1. \(2 \pi \times 10^{-2}~\text{Wb}\)
2. \(3 \pi \times 10^{-4}~\text{Wb}\)
3. \(5 \pi \times 10^{-5}~\text{Wb}\)
4. \(5 \pi \times 10^{-4}~\text{Wb}\)
A conducting square loop of side \(L\) and resistance \(R\) moves in its plane with a uniform velocity \(v\) perpendicular to one of its sides. A magnetic induction \(B\) constant in time and space, pointing perpendicular and into the plane of the loop exists everywhere. The current induced in the loop is:
| 1. | \(\dfrac{Blv}{R}\) clockwise | 2. | \(\dfrac{Blv}{R}\) anticlockwise |
| 3. | \(\dfrac{2Blv}{R}\) anticlockwise | 4. | zero |
A conducting wireframe is placed in a magnetic field that is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced current in wires \(AB\) and \(CD\) are:
| 1. | \(B\) to \(A\) and \(D\) to \(C\) |
| 2. | \(A\) to \(B\) and \(C\) to \(D\) |
| 3. | \(A\) to \(B\) and \(D\) to \(C\) |
| 4. | \(B\) to \(A\) and \(C\) to \(D\) |
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. \(\frac{4 B_{0}}{A_{0} t}\)
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. |
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