A : There is no energy transferred by standing waves .
R : The total energy of each of incident and reflected wave .

Answer

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step-by-Step Solution:

**Step 1: Understand the Assertion (A)**
The assertion states that "there is no energy transferred by standing waves."
- A standing wave is formed by the interference of two waves traveling in opposite directions. In a standing wave, certain points (nodes) do not move, while others (antinodes) oscillate with maximum amplitude.
- The key point is that the energy does not propagate through the medium in the form of standing waves. Instead, the energy is localized around the nodes and antinodes, resulting in no net energy transfer across the medium.

**Step 2: Understand the Reason (R)**
The reason states that "the total energy of each incident and reflected wave is unchanged."
- When a wave encounters a boundary, part of it is reflected and part is transmitted. The energy of the incident wave is conserved, meaning the total energy remains constant before and after the interaction.
- Since the incident wave's energy is equal to the reflected wave's energy, the total energy remains unchanged. This conservation of energy in the incident and reflected waves contributes to the formation of standing waves without any net energy transfer.

**Step 3: Analyze the Relationship Between A and R**
- Both the assertion and the reason are true. The assertion correctly describes the nature of standing waves, and the reason explains why there is no energy transfer, as the total energy of the incident and reflected waves remains constant.

**Conclusion:**
Both the assertion (A) and the reason (R) are true, and the reason correctly explains the assertion. Thus, the correct answer is that both A and R are true.

### Final Answer:
Both assertion and reason are true.

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