A resistor connected to a 12V battery draws a current of 2A. The energy dispatched in the resistor in 5 minutes is ___.

Analyze the question: A 12 V battery drives a 2 A current through a resistor. We need the electrical energy dissipated in 5 minutes.

Concept: Electrical energy dissipated is

E = V × I × t

where V is voltage (volts), I is current (amperes), and t is time (in seconds). Always convert minutes to seconds before substituting.

Solution:

1. Convert time: t = 5 minutes = 5 × 60 = 300 s
2. Calculate power: P = VI = 12 × 2 = 24 W
3. Calculate energy: E = P × t = 24 × 300 = 7,200 J

Check using another form:

• R = V/I = 12/2 = 6 Ω
• E = I²Rt = (2)² × 6 × 300 = 4 × 6 × 300 = 7,200 J ✓

Answer: C. 7,200 J

Exam tip: In most energy and power questions, the common mistake is forgetting to convert minutes to seconds. If you used 5 minutes directly, you would get 120 J, which is not an option. Remember "VIt" and always convert time to seconds first. Note that option D (14,400 J) is what you would get if you mistakenly used 10 minutes, so check your time conversion carefully.