Duration of induced .current produced in electromagnetic field is:

Options

A. with magnetic flux :
B. perpendicular to magnetic flux
C. opposing magnetic flux
D. both (b) and (c)

Explanation

To solve the question regarding the duration of induced current produced in an electromagnetic field, we need to understand the principles of electromagnetic induction, particularly Faraday's law of electromagnetic induction and Lenz's law.

### Step-by-Step Solution:

1. **Understanding Electromagnetic Induction**:
- Electromagnetic induction occurs when a change in magnetic flux through a circuit induces an electromotive force (EMF) in that circuit. According to Faraday's law, the induced EMF is proportional to the rate of change of magnetic flux.

2. **Faraday's Law**:
- Mathematically, Faraday's law can be expressed as:
\[ \text{EMF} = -\frac{d\Phi_B}{dt} \]
where \(\Phi_B\) is the magnetic flux.

3. **Lenz's Law**:
- Lenz's law states that the direction of the induced current will be such that it opposes the change in magnetic flux that produced it. This is a consequence of the conservation of energy.

4. **Duration of Induced Current**:
- The duration of the induced current depends on how quickly the magnetic flux changes. If the change in magnetic flux is rapid, the induced current will also be present for a shorter duration. Conversely, a slow change in magnetic flux will result in a longer duration of induced current.

5. **Factors Affecting Duration**:
- The duration of the induced current is influenced by:
- The rate of change of the magnetic field.
- The resistance of the circuit.
- The inductance of the circuit.

6. **Conclusion**:
- The duration of the induced current is not fixed; it varies based on the factors mentioned above. However, it is essential to remember that the induced current will always oppose the change in magnetic flux, as per Lenz's law.

### Final Answer:
The duration of induced current produced in an electromagnetic field is variable and depends on the rate of change of magnetic flux, resistance, and inductance in the circuit.