Choose the correct options regarding a galvanometer

Options

A. It measures current
B. It is marked with positive and negative polarity
C. The deflection in the galvanometer is proportional to the current
D. Zero is marked at the middle of instrument

Answer

To solve the question regarding the correct options about a galvanometer, we need to analyze the properties and functions of a galvanometer step by step.

### Step-by-Step Solution:

1. **Definition of Galvanometer**:
A galvanometer is an electro-mechanical instrument used for detecting and indicating the presence of electric current. It does not measure the current in absolute terms but indicates its presence through deflection.

**Hint**: Remember that a galvanometer detects current rather than measuring its magnitude.

2. **Functionality**:
The galvanometer operates by producing a rotary deflection of a pointer in response to the electric current flowing through it. The amount of deflection is proportional to the amount of current.

**Hint**: Focus on the relationship between current and deflection; it’s proportional.

3. **Zero Mark Position**:
The zero mark on a galvanometer is typically located at the center of the scale. This means that deflections to the left indicate one direction of current, while deflections to the right indicate the opposite direction.

**Hint**: Visualize the scale of the galvanometer; the center represents zero current.

4. **Direction of Current**:
A galvanometer is primarily used to measure the direction of electric current, not its magnitude. This means it indicates whether the current is flowing in a positive or negative direction.

**Hint**: Remember that the galvanometer shows the direction of current flow rather than its strength.

5. **Evaluation of Options**:
- **Option 1**: "It measures current" - This is incorrect. A galvanometer does not measure current; it detects it.
- **Option 2**: "It is marked with positive and negative polarity" - This is also incorrect. While it indicates direction, it does not have a positive or negative marking like a voltmeter.
- **Option 3**: "The deflection in the galvanometer is proportional to the current" - This is correct. The deflection indicates the presence and direction of the current.
- **Option 4**: "Zero is marked at the middle of the instrument" - This is correct. The zero mark is at the center, indicating no current flow.

### Conclusion:
The correct options regarding a galvanometer are:
- The deflection in the galvanometer is proportional to the current (Correct).
- Zero is marked at the middle of the instrument (Correct).

**Final Answer**: The correct options are:
- The deflection in the galvanometer is proportional to the current.
- Zero is marked at the middle of the instrument.