A 75 W light bulb with a resistance of 179 Ω is connected to a power supply with a 119 V. What is the internal resistance of the power supply? Express the answer with one decimal place.

Question

anonymous · Answer

There are two ways to solve this problem, one is using KCL, the other one is calculating the total current flowing into the circuit, then we find the total resistance, then we can find the internal resistance of the power supply by subtracting the load resistance from the total resistance...

anonymous · Answer

$$I_{total} = \frac{V_{total}}{R_{total}}$$

anonymous · Answer

$$R_{total} = \frac{V_{total}}{I_total}$$

anonymous · Answer

$$R_{Internal} = R_{total} - R_L$$