Final answer:
The power dissipated by a 20Ω resistor with a 0.25 A current is found using the formula P = I²R, yielding 1.25 watts. The correct answer is option D.
Step-by-step explanation:
The question relates to the power dissipation in resistors, which is a fundamental concept in electric circuits within Physics. To find the power dissipated by a resistor when a current runs through it, you can use the formula P = I²R, where P is the power in watts, I is the current in amperes, and R is the resistance in ohms. In this scenario, the resistor has an electrical resistance of 20Ω and there is a current of 0.25 A flowing through it.
Applying the formula, we get:
P = I²R = (0.25 A)² × 20Ω = 1.25 watts
Therefore, the correct answer is D. 1.25 watts.