The phosphor bronze strip is used in a moving coil galvanometer because

Options

A. Its torsional constant is small
B. It is easily available
C. It is paramagnetic
D. it is diamagnetic

Answer

**Step-by-Step Solution:**

1. **Understanding the Purpose of the Phosphor Bronze Strip:**
The phosphor bronze strip is primarily used in a moving coil galvanometer for several reasons. It serves as a conductor for electricity to the coil, supports the coil structure, and helps return the coil to its original position after it has moved.

2. **Properties of Phosphor Bronze:**
- **Torsional Constant:** The torsional constant of a material indicates how much it can twist under a given torque. A smaller torsional constant means that the material can twist more easily, which is beneficial for the sensitivity of the galvanometer.
- **Oxidation Resistance:** Phosphor bronze has low oxidation rates, which means it maintains its conductive properties over time without degrading.
- **Magnetic Properties:** It is non-magnetic, meaning it does not get attracted to magnetic fields, which is essential for the proper functioning of the galvanometer.

3. **Conclusion:**
Given these properties, the phosphor bronze strip is ideal for use in a moving coil galvanometer because its small torsional constant allows for better sensitivity and response, while its resistance to oxidation and non-magnetic nature ensures durability and accuracy.

4. **Final Answer:**
The phosphor bronze strip is used in a moving coil galvanometer because its torsional constant is small.

---