Final answer:
To calculate power in a DC circuit with known resistance and current, use the formula P = I^2R, derived by combining Ohm's law (V = IR) with the power equation (P = IV).
Step-by-step explanation:
The formula used to compute power in a DC circuit when you only know resistance and current is P = I2R. This is derived from combining Ohm's law, V = IR, with the power equation P = IV. Essentially, by eliminating the voltage using Ohm's law, we arrive at the formula for power that depends solely on the current and the resistance in the circuit.
Ohm's law expresses the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit, where voltage is equal to the product of the current and the resistance (V=IR). Considering the equation for power, P = IV, and replacing V with IR from Ohm's law, we get P = I(IR) = I2R. This means that for any resistor within a DC circuit, if you know the current flowing through it and its resistance, you can calculate the power dissipation using this formula.