(A) : In an electromagnetic wave, the electric and magnetic fields oscillate in phase (R) : In an electromagnetic wave, the electric and magnetic fields oscillate out of phase.

Options

A. Both 'A' and 'R' are true and 'R' is the correct explanation of 'A'.
B. Both 'A' and ’R' are true and 'R' is not the correct explanation of 'A
C. A' is true and 'R' is false
D. 'A' is false and R' is true

Answer

To solve the question, we need to analyze the statements regarding the electric and magnetic fields in an electromagnetic wave.

### Step-by-Step Solution:

1. **Understanding Electromagnetic Waves**:
- Electromagnetic waves consist of oscillating electric and magnetic fields that propagate through space. These fields are perpendicular to each other and to the direction of wave propagation.

2. **Direction of Fields**:
- In an electromagnetic wave, if we consider the direction of propagation to be along the x-axis, the electric field (E) can be oriented along the y-axis, and the magnetic field (B) can be oriented along the z-axis.

3. **Phase Relationship**:
- The electric field and the magnetic field oscillate in such a way that their peaks and troughs occur at the same time. This means that when the electric field reaches its maximum value, the magnetic field also reaches its maximum value simultaneously.

4. **Conclusion about Phase**:
- Since both fields reach their maximum and minimum values at the same time, they are said to be "in phase." This means that the phase difference between the electric and magnetic fields is zero.

5. **Evaluating the Statements**:
- Statement (A): "In an electromagnetic wave, the electric and magnetic fields oscillate in phase." - This statement is **true**.
- Statement (R): "In an electromagnetic wave, the electric and magnetic fields oscillate out of phase." - This statement is **false**.

6. **Final Answer**:
- Therefore, the correct conclusion is that (A) is true and (R) is false.