The thermal power of the electric current (in watts) can be calculated using the formula N = U ^ 2 / R

The thermal power of the electric current (in watts) can be calculated using the formula N = U ^ 2 / R, where U is the voltage of the electric circuit in volts, R is the resistance of the electric circuit in ohms. Using this formula, find the voltage of an electrical circuit (in volts), the thermal power of which is 0.03 watts and the resistance is 3 ohms.

N = U ^ 2 / R
From this formula, you can deduce the voltage, then substitute the values and find the result:
U ^ 2 = N * R
Now we substitute the values we know:
N = 0.03 Watt;
R = 3 Ohm:
U ^ 2 = 0.03 * 3;
U ^ 2 = 0.09
U = square root of 0.09 = 0.3 volts.
Answer: U = 0.3 Volts.