An electromagnetic wave is generated by

Options

A. Any moving charge
B. Any accelerating charge
C. Only a charge with changing acceleration
D. Only a charge moving in a circle

Answer

**Step-by-Step Solution:**

1. **Understanding Electromagnetic Waves**:
Electromagnetic waves are generated by the movement of electric charges. To understand how these waves are produced, we need to consider the behavior of charges under different conditions.

2. **Analyzing the First Option - Any Moving Charge**:
- If we take a charge (like an electron) moving with a constant velocity, it generates a constant electric current.
- A constant current produces a constant magnetic field around it.
- Since both the electric field and magnetic field are constant, there is no change in the fields over time. Therefore, no electromagnetic wave is generated from a charge moving at constant velocity.

3. **Analyzing the Second Option - Any Accelerating Charge**:
- If the charge is accelerating (i.e., its velocity is changing), it produces a varying electric field.
- An accelerating charge generates a changing magnetic field as well.
- According to Maxwell's equations, a changing electric field produces a magnetic field, and a changing magnetic field produces an electric field. This interdependence is what leads to the formation of electromagnetic waves.
- Thus, this option is correct: an electromagnetic wave is generated by any accelerating charge.

4. **Analyzing the Third Option - Only a Charge with Changing Acceleration**:
- This option suggests that only a charge with changing acceleration can generate electromagnetic waves.
- However, it is not necessary for the acceleration to change. A charge can have constant acceleration (like in uniform circular motion) and still produce electromagnetic waves.
- Therefore, this option is not correct.

5. **Conclusion**:
- The only correct option for generating electromagnetic waves is "any accelerating charge."

**Final Answer**: An electromagnetic wave is generated by any accelerating charge.

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