Which one of the following gives the value of the magnetic field according to Biot-Savart’s law?
1. | \(\frac{\mathrm{i} \Delta \mathrm{l} \sin (\theta)}{\mathrm{r}^2} \) | 2. | \(\frac{\mu_0}{4 \pi} \frac{\mathrm{i} \Delta \mathrm{l} \sin (\theta)}{\mathrm{r}} \) |
3. | \(\frac{\mu_0}{4 \pi} \frac{\mathrm{i} \Delta \mathrm{l} \sin (\theta)}{\mathrm{r}^2} \) | 4. | \(\frac{\mu_0}{4 \pi} \mathrm{i} \Delta \mathrm{l} \sin (\theta)\) |
What is the magnetic field at point O in the figure?
1.
2.
3.
4.
If the current is flowing in the south direction along a power line, then what will be the direction of the magnetic field above the power line (neglecting the earth's field)?
1. | South | 2. | East |
3. | North | 4. | West |
If a wire in the form of a square with a side ‘a’ carries a current i, then the magnetic induction at the centre of the square wire will be:
(Magnetic permeability of free space = )
1. | \(\frac{\mu _{0}i}{2\pi a}\) | 2. | \(\frac{\mu _{0}i\sqrt2}{\pi a}\) |
3. | \(\frac{2\sqrt2\mu _{0}i}{\pi a}\) | 4. | \(\frac{\mu _{0}i}{\sqrt2\pi a}\) |
A proton and an α- particle enter a uniform magnetic field perpendicularly at the same speed. If a proton takes 25 μs to make 5 revolutions, then the periodic time for the α-particle will be:
1. 50 s
2. 25 s
3. 10 s
4. 5 s
Which among the following options needs to be decreased to increase the sensitivity of a moving coil galvanometer?
1. | the number of turns in the coil. | 2. | the area of the coil. |
3. | the magnetic field. | 4. | the couple per unit twist of the suspension. |
In a hydrogen atom, the electron makes 6.6×1015 rev/sec around the nucleus in an orbit of radius 0.528 Å. What will (A-m2) its magnetic moment be?
1.
2.
3.
4.
What is a representation of the magnetic field caused by a straight conductor with a uniform cross-section and a steady current of radius 'a'?
1. | 2. | ||
3. | 4. |
A particle of charge q and mass m is moving along the x-axis with a velocity of v and enters a region of electric field E and magnetic field B as shown in the figure below. For which figure is the net force on the charge zero?
1. | 2. | ||
3. | 4. |
A current-carrying wire is placed in a uniform magnetic field in the shape of the curve \(y= \alpha sin ({\pi x \over L}),~0 \underline{<}x \underline{<}~2L\)
. What will be the force acting on the wire?
1. | \(iBL \over \pi\) | 2. | \(iBL \pi\) |
3. | \(2iBL \) | 4. | Zero |