How many watts of electrical power are consumed by a 12 VDC light bulb that draws 0.2 amperes?
The correct answer is A: 2.4 watts. The watts of electrical power consumed by a 12 VDC light bulb that draws 0.2 amperes is 2.4 watts. Power = V × I = 12 × 0.2 = 2.4 watts. For amateur radio operators, this is a basic power calculation. Understanding this helps when calculating power consumption.
Exam Tip
Power = V × I. 12V, 0.2A: P = 12 × 0.2 = 2.4W. Think 'P'ower = 'V'oltage × 'I'nterest (current). Use P = V × I formula. Not 24W (2A), not 6W (0.5A), not 60W (5A) - just 2.4W (0.2A).
Memory Aid
"Power = V × I. 12V, 0.2A: P = 12 × 0.2 = 2.4W. Think 'P'ower = 'V'oltage × 'I'nterest. Use P = V × I formula for power calculation. Standard power formula."
Real-World Application
A 12-volt light bulb draws 0.2 amperes. Power consumed = V × I = 12 × 0.2 = 2.4 watts. The bulb consumes 2.4 watts of power. This is a basic power calculation using P = V × I.
Key Concepts
Why Other Options Are Wrong
Option B (24 watts): Incorrect. 24 watts would be if current was 2 amps, not 0.2 amps. 12V × 2A = 24W, but current is 0.2A.
Option C (6 watts): Incorrect. 6 watts would be if current was 0.5 amps, not 0.2 amps. 12V × 0.5A = 6W, but current is 0.2A.
Option D (60 watts): Incorrect. 60 watts would be if current was 5 amps, not 0.2 amps. 12V × 5A = 60W, but current is 0.2A.
题目解析
The correct answer is A: 2.4 watts. The watts of electrical power consumed by a 12 VDC light bulb that draws 0.2 amperes is 2.4 watts. Power = V × I = 12 × 0.2 = 2.4 watts. For amateur radio operators, this is a basic power calculation. Understanding this helps when calculating power consumption.
考试技巧
Power = V × I. 12V, 0.2A: P = 12 × 0.2 = 2.4W. Think 'P'ower = 'V'oltage × 'I'nterest (current). Use P = V × I formula. Not 24W (2A), not 6W (0.5A), not 60W (5A) - just 2.4W (0.2A).
记忆口诀
Power = V × I. 12V, 0.2A: P = 12 × 0.2 = 2.4W. Think 'P'ower = 'V'oltage × 'I'nterest. Use P = V × I formula for power calculation. Standard power formula.
实际应用示例
A 12-volt light bulb draws 0.2 amperes. Power consumed = V × I = 12 × 0.2 = 2.4 watts. The bulb consumes 2.4 watts of power. This is a basic power calculation using P = V × I.
错误选项分析
Option B (24 watts): Incorrect. 24 watts would be if current was 2 amps, not 0.2 amps. 12V × 2A = 24W, but current is 0.2A. Option C (6 watts): Incorrect. 6 watts would be if current was 0.5 amps, not 0.2 amps. 12V × 0.5A = 6W, but current is 0.2A. Option D (60 watts): Incorrect. 60 watts would be if current was 5 amps, not 0.2 amps. 12V × 5A = 60W, but current is 0.2A.
知识点
Power calculation, P = V × I, Ohm's Law, Power consumption
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.