To determine which fuse can be safely used with a 3000W electric cooker on a 200V mains circuit, we need to calculate the current that the cooker will draw when it is operating. ### Step 1: Calculate the Current The power (P) consumed by an electrical device can be calculated using the formula: \[ P = V \times I \] Where: - \( P \) is the power in watts (W), - \( V \) is the voltage in volts (V), - \( I \) is the current in amperes (A). We can rearrange this formula to solve for current: \[ I = \frac{P}{V} \] Substituting the values for the electric cooker: \[ I = \frac{3000W}{200V} = 15A \] ### Step 2: Determine the Suitable Fuse Rating Fuses are designed to protect electrical circuits by breaking the circuit if the current exceeds a certain level. The fuse rating should be higher than the normal operating current of the device but low enough to protect the circuit from overload. In this case, the electric cooker draws 15A. Therefore, we need a fuse that can handle this current safely. ### Step 3: Evaluate the Options Now, let's evaluate the options provided: - **A. 2A**: This fuse rating is too low. It would blow immediately when the cooker is turned on, as the cooker draws 15A. - **B. 5A**: This fuse rating is also too low. Similar to the 2A fuse, it would blow as soon as the cooker is used, since 15A exceeds 5A. - **C. 10A**: This fuse rating is still too low. The cooker will draw 15A, which is above the 10A rating, causing the fuse to blow. - **D. 20A**: This fuse rating is appropriate. It is higher than the 15A that the cooker draws, meaning it will not blow under normal operation. However, it is still low enough to provide protection against potential overloads. ### Conclusion The correct option is **D. 20A**. This fuse can safely be used with the 3000W electric cooker on a 200V mains circuit because it can handle the current drawn by the cooker without blowing. ### Summary of Why Other Options Are Incorrect - **A. 2A**: Too low; would blow immediately. - **B. 5A**: Too low; would blow immediately. - **C. 10A**: Too low; would blow immediately. - **D. 20A**: Correct; can handle 15A safely. ### Revision Summary - Calculate current using \( I = \frac{P}{V} \). - A fuse must be rated higher than the device's operating current. - A 3000W cooker at 200V draws 15A. - The suitable fuse rating is 20A, as it is above 15A and provides protection.