Write two reasons, why a galvanometer cannot be used as such to measure current in a given circuit.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is the correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Explanation

To answer the question of why a galvanometer cannot be used directly to measure current in a circuit, we can break it down into two main reasons:

### Step-by-Step Solution:

1. **Sensitivity to Current**:
- A galvanometer is designed to detect very small currents, typically in the microampere range. It has a figure of merit (current sensitivity) that indicates the amount of current required to produce a unit deflection in the galvanometer's needle. For example, a galvanometer may require only a few microamperes to show a deflection, but to achieve full-scale deflection, it may require several milli-amperes.
- **Conclusion**: Because of its high sensitivity, a galvanometer is not suitable for measuring larger currents, as even a small increase in current can lead to a significant deflection, making it difficult to obtain accurate readings.

2. **High Internal Resistance**:
- A galvanometer has a relatively high internal resistance compared to an ammeter. When connected in a circuit, this high resistance can significantly reduce the current flowing through the circuit.
- **Conclusion**: The presence of high resistance means that the galvanometer will not allow the full current to pass through, leading to an inaccurate measurement. This is because the current measured will be lower than the actual current in the circuit due to the voltage drop across the galvanometer.

### Summary:
- **Reason 1**: A galvanometer is too sensitive and can only measure small currents accurately, leading to difficulties when measuring larger currents.
- **Reason 2**: The high internal resistance of a galvanometer affects the current in the circuit, resulting in inaccurate measurements.