MCAT Physics Question 86: Answer and Explanation
Home > MCAT Test > MCAT physics practice tests
Test Information
- Use your browser's back button to return to your test results.
- Do more MCAT physics practice tests.
Question: 86
11. A 10 Ω resistor carries a current that varies as a function of time as shown. How much energy has been dissipated by the resistor after 5 s?
- A. 40 J
- B. 50 J
- C. 80 J
- D. 120 J
Correct Answer: D
Explanation:
Power is energy dissipated per unit time; therefore, the energy dissipated is E = PΔt. In the five-second interval during which the resistor is active, it has a 2 A current for three of those seconds. The power dissipated by a resistor R carrying a current I is P = I2R. Therefore, the energy dissipated is
E = I2RΔt =(2 A)2(10 ?)(3 s)= 4 × 10 × 3 = 120 J