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. |