Resistors with resistance R = 20 Ohm and R = 40 Ohm are connected in series.

Resistors with resistance R = 20 Ohm and R = 40 Ohm are connected in series. What is the total current in the resistors if the voltage across the first resistor is 10V?

Determine the current in the first resistor

I1 = U1 / R1 = 10/20 = 0.5 A.

Power at the first resistor

W1 = I1 * U1 = 0.5 * 10 = 5 W.

When connected in series, the current is the same in all sections of the circuit

I2 = I1.

Then

U2 = I2 * R2 = 0.5 * 40 = 20 V;

W2 = I2 * U2 = 0.5 * 20 = 10 W.

Answer: the power on the first resistor is 5 W, on the second 10 W.