When power is drawn from the secondary coil of the transformer, the dynamic resistance

Options

A. increases
B. decreases
C. remains unchanged
D. changes erratically

Answer

To solve the question regarding the dynamic resistance of a transformer when power is drawn from the secondary coil, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Dynamic Resistance**:
Dynamic resistance refers to the resistance of a circuit element when a varying current flows through it. In the context of a transformer, it relates to how the power drawn from the secondary coil affects the overall resistance.

2. **Establish the Relationship Between Power and Dynamic Resistance**:
It is important to note that power (P) in a circuit is directly proportional to dynamic resistance (R_d). This means:
\[ P \propto R_d \]
If power increases, dynamic resistance increases, and if power decreases, dynamic resistance decreases.

3. **Analyze the Situation**:
The question states that power is being drawn from the secondary coil of the transformer. This action implies that the overall power in the circuit is being utilized or decreased.

4. **Apply the Relationship**:
Since power is drawn from the secondary coil, we can conclude that the power in the overall circuit is decreasing. According to the relationship established in step 2, if the power decreases, the dynamic resistance must also decrease.

5. **Conclude the Answer**:
Therefore, when power is drawn from the secondary coil of the transformer, the dynamic resistance decreases. The correct answer is:
\[ \text{Dynamic Resistance: Decreases} \]

### Final Answer:
The dynamic resistance decreases when power is drawn from the secondary coil of the transformer.

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