Q. No.A moving charge produces:
1. electric field only
2. magnetic field only
3. both of them
4. none of them
| 1. | Fleming's left-hand rule | 2. | Biot-Savart law |
| 3. | Gauss's law | 4. | Lenz's law |
Biot-Savart law indicates that the moving electrons (velocity \(v\)) produce a magnetic field \(B\) such that:
| 1. | \(B\perp v\). |
| 2. | \(B\parallel v\). |
| 3. | it obeys inverse cube law. |
| 4. | it is along the line joining the electron and point of observation. |
An element of length \(0.05{\hat i}~\text m\) is placed at the origin as shown in the figure and carries a current of \(10~\text{A}.\) The magnetic field at a point \(1~\text{m}\) away in a direction perpendicular to the element is:
| 1. | \(4.5\times 10^{-8}~\text{T}\) | 2. | \(5.5\times 10^{-8}~\text{T}\) |
| 3. | \(5.0\times 10^{-8}~\text{T}\) | 4. | \(7.5\times 10^{-8}~\text{T}\) |
| 1. | field is the same every where around the conductor. |
| 2. | field is directly proportional to the square of the current flowing in the conductor. |
| 3. | field obeys the inverse square law of distance. |
| 4. | magnetic field strength was maximum on the axis of the current conductor. |
The magnetic induction due to an infinitely long straight wire carrying a current \(i\) at a distance \(r\) from the wire is given by:
1. \( B =\dfrac{\mu_0}{4 \pi} \dfrac{2 i}{r} \)
2. \(B =\dfrac{\mu_0}{4 \pi} \dfrac{r}{2 i} \)
3. \(B =\dfrac{4 \pi}{\mu_0} \dfrac{2 i}{r} \)
4. \(B =\dfrac{4 \pi}{\mu_0} \dfrac{r}{2 i}\)
A circular coil \(A \) has a radius \(R\) and the current flowing through it is \(I.\) Another circular coil \(B\) has a radius \(2R\) and if \(2I\) is the current flowing through it, then the magnetic fields at the centre of the circular coil are in the ratio of:
1. \(4:1\)
2. \(2:1\)
3. \(3:1\)
4. \(1:1\)
| 1. | \(\dfrac{\mu_0i}{4}\Big(\dfrac{1}{R_1}-\dfrac{1}{R_2}\Big)\) | 2. | \(\dfrac{\mu_0i}{4}\Big(\dfrac{1}{R_1}+\dfrac{1}{R_2}\Big)\) |
| 3. | \(\dfrac{\mu_0i}{4}({R_1}-{R_2})\) | 4. | \(\dfrac{\mu_0i}{4}({R_1}+{R_2})\) |
1. \(nB\)
2. \(n^2B\)
3. \(2nB\)
4. \(2n^2B\)
1. 5 A
2. 2.5 A
3. 7 A
4. 10 A
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