52. In figure «A» of the illustration, 12 volts is applied to the circuit where the resistance of R1 is 10 ohms and R2 is 10 ohms. what is the voltage across R2 when the switch is closed

The voltage across R2 is 6 volts. In a series circuit with equal resistances, the voltage divides equally across each resistor. The total resistance is 20 ohms, resulting in a current of 0.6 amps. Applying Ohm's Law to R2 (V = I x R) yields a voltage of 6 volts.