A rod of length \(l\) rotates with a small but uniform angular velocity \(\omega\) about its perpendicular bisector. A uniform magnetic field \(B\) exists parallel to the axis of rotation. The potential difference between the centre of the rod and an end is:
1. zero
2. \(\frac{1}{8} \omega {B} l^{2}\)
3. \(\frac{1}{2} \omega {B} l^{2}\)
4. \(B\omega l^2\)
A rod of length \(l\) rotates with a uniform angular velocity \(\omega\) about its perpendicular bisector. A uniform magnetic field \(B\) exists parallel to the axis of rotation. The potential difference between the two ends of the rod is:
1. zero
2. \(\frac{1}{2}Bl\omega ^{2}\)
3. \(Bl\omega ^{2}\)
4. \(2Bl\omega ^{2}\)
Consider the following statements:
(A): | An emf can be induced by moving a conductor in a magnetic field. |
(B): | An emf can be induced by changing the magnetic field. |
1. | Both A and B are True |
2. | A is True but B is False |
3. | B is True but A is False |
4. | Both A and B are False |
Consider the situation shown in the figure. The wire AB is slid on the fixed rails with a constant velocity. If the wire AB is replaced by a semicircular wire, the magnitude of the induced current will
1. increase
2. remain the same
3. decrease
4. increase or decrease depending on whether the-semicircle bulges towards the resistance or away from it
A conducting rod is moved with a constant velocity \(v\) in a magnetic field. A potential difference appears across the two ends,
a. | \(\overrightarrow v \|\overrightarrow l\) | ifb. | if \(\overrightarrow v \|\overrightarrow B\) |
c. | \(\overrightarrow l \|\overrightarrow B\) | ifd. | none of these |
Choose the correct option:
1. | (a), (b) | 2. | (b), (c) |
3. | (d) only | 4. | (a), (d) |
A metal sheet is placed in front of a strong magnetic pole. A force is needed to:
(a) | hold the sheet there if the metal is magnetic. |
(b) | hold the sheet there if the metal is nonmagnetic. |
(c) | move the sheet away from the pole with uniform velocity if the metal is magnetic. |
(d) | move the sheet away from the pole with uniform velocity if the metal is nonmagnetic. |
Neglect any effect of paramagnetism, diamagnetism and gravity.
Choose the correct option.
1. | (a), (c), (d) |
2. | (b), (c), (a) |
3. | (c), (d), (a) |
4. | (a), (d), (c) |
A rod AB moves with a uniform velocity v in a uniform magnetic field as shown in the figure.
(a) The rod becomes electrically charged.
(b) The end A becomes positively charged.
(c) The end B becomes positively charged.
(d) The rod becomes hot because of Joule heating.
Choose the correct option
1. (a), (b)
2. (b) only
3. (c), (d)
4. (a), (d)