To determine the sensitivity of a moving coil galvanometer, we need to understand the relationship between the current, the deflection angle, and the sensitivity itself. Let's break this down step-by-step. ### Step 1: Understanding Sensitivity The sensitivity of a galvanometer is defined as the amount of deflection (in degrees or radians) per unit of current (in amperes) that flows through it. Mathematically, it can be expressed as: \[ \text{Sensitivity} = \frac{\text{Deflection (degrees)}}{\text{Current (A)}} \] ### Step 2: Given Values From the problem, we have: - Full-scale deflection = 30 degrees - Corresponding current for full-scale deflection = 3 A ### Step 3: Calculating Sensitivity Now, we can plug these values into the sensitivity formula: \[ \text{Sensitivity} = \frac{30 \text{ degrees}}{3 \text{ A}} = 10 \text{ degrees/A} \] ### Step 4: Final Answer Thus, the sensitivity of the galvanometer is **10.0 degrees/A**. Therefore, the correct option is **D**. ### Step 5: Analyzing Other Options Let’s evaluate the other options to understand why they are incorrect: - **Option A: 33.0** - This value does not correspond to the calculated sensitivity. It suggests a much higher sensitivity than what is derived from the given deflection and current. - **Option B: 0.1** - This value implies that the galvanometer would only deflect 0.1 degrees for every ampere of current, which is significantly lower than the actual sensitivity calculated. This would make the galvanometer very insensitive and impractical for most applications. - **Option C: 90.0** - This value suggests an extremely high sensitivity, indicating that the galvanometer would deflect 90 degrees for just 1 A of current. This is not supported by the given data and is unrealistic for a typical galvanometer. ### Common Pitfalls - **Misunderstanding Sensitivity**: Students often confuse sensitivity with the total deflection or the maximum current. Remember, sensitivity is specifically the deflection per unit current. - **Incorrect Units**: Ensure that you are consistent with units when calculating sensitivity. Here, we used degrees for deflection and amperes for current. - **Ignoring Full-Scale Deflection**: Always pay attention to the full-scale deflection value, as it is crucial for determining the sensitivity. ### Revision Summary - Sensitivity of a galvanometer is calculated as deflection per unit current. - For this problem, sensitivity = 30 degrees / 3 A = 10 degrees/A. - The correct answer is **D: 10.0**. - Always check units and definitions to avoid common mistakes in calculations.