The source of time varying magnetic field may be
(A) a permanent maget
(B) an electric field changing linearly with time
(C) direct current
(D) a decelarating charge particle
(E) an antenna fed with a digital signal
Choose the correct answer from the options given below:

Options

A. `(B) and (D) only`
B. `(C) and (E) only`
C. `(E) only`
D. `(D) only`

Answer

To solve the question regarding the source of a time-varying magnetic field, we need to analyze each option provided:

1. **Permanent Magnet**: A permanent magnet produces a constant magnetic field. Since it does not change with time, it cannot be a source of a time-varying magnetic field.

2. **Electric Field Changing Linearly with Time**: According to Faraday's law of electromagnetic induction, a changing electric field can induce a magnetic field. Therefore, this option can be a source of a time-varying magnetic field.

3. **Direct Current (DC)**: A direct current flows steadily and does not change with time. Thus, it does not produce a time-varying magnetic field.

4. **Decelerating Charge Particle**: A decelerating charge particle experiences a change in velocity, which means its magnetic field is also changing with time. Therefore, this can be considered a source of a time-varying magnetic field.

5. **Antenna Fed with a Digital Signal**: Antennas transmit signals that vary with time, which means they can also produce time-varying magnetic fields.

Now, let's summarize the findings:

- **Permanent Magnet**: No (constant field)
- **Electric Field Changing Linearly with Time**: Yes (can induce a magnetic field)
- **Direct Current**: No (constant current)
- **Decelerating Charge Particle**: Yes (changing velocity)
- **Antenna Fed with a Digital Signal**: Yes (time-varying signal)

From the analysis, the correct options that can be sources of a time-varying magnetic field are:
- (B) Electric Field Changing Linearly with Time
- (D) Decelerating Charge Particle
- (E) Antenna Fed with a Digital Signal

### Final Answer:
The correct options are (B), (D), and (E).