Question

How much energy is dissipated by the 1.5–ohm resistor in 60 seconds?

Answer 1

First, you need to replace the three R2 resistors with a single equivalent resistance to figure out the total current from the battery. The three R2 resistors are connected in parallel, so the equivalent resistance RE is (1/R2 + 1/R2 + 1/R2) ^ -1, or 9.67Ω.