What is the current in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?
The correct answer is D: 1.5 amperes. In a circuit with an applied voltage of 120 volts and a resistance of 80 ohms, the current is 1.5 amperes. Using Ohm's Law: I = E / R = 120 / 80 = 1.5 amperes.
This calculation uses Ohm's Law rearranged to solve for current. When you know voltage and resistance, you divide voltage by resistance to find current. The formula I = E / R shows that current increases when voltage increases or when resistance decreases. This is essential for understanding circuit behavior and calculating power consumption (P = E × I = 120 × 1.5 = 180 watts).
Exam Tip
Current = Voltage / Resistance. Remember: I = 120V / 80Ω = 1.5A. Divide voltage by resistance to find current.
Memory Aid
"**I** = **1**20V / **8**0Ω = **1**.**5**A (think '120/80 = 1.5')"
Real-World Application
You're testing a power amplifier. You apply 120 volts and measure 80 ohms resistance. Using I = E / R, you calculate the current: I = 120 / 80 = 1.5 amperes. This helps you verify the amplifier's operation and calculate power consumption.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. 9600 amperes would be multiplying voltage and resistance (120 × 80), which is mathematically incorrect. Current is voltage divided by resistance.
Option B: Incorrect. 200 amperes would be adding voltage and resistance (120 + 80), which is mathematically invalid.
Option C: Incorrect. 0.667 amperes would be dividing resistance by voltage (80 / 120), which is the inverse of the correct formula.
题目解析
The correct answer is D: 1.5 amperes. In a circuit with an applied voltage of 120 volts and a resistance of 80 ohms, the current is 1.5 amperes. Using Ohm's Law: I = E / R = 120 / 80 = 1.5 amperes. This calculation uses Ohm's Law rearranged to solve for current. When you know voltage and resistance, you divide voltage by resistance to find current. The formula I = E / R shows that current increases when voltage increases or when resistance decreases. This is essential for understanding circuit behavior and calculating power consumption (P = E × I = 120 × 1.5 = 180 watts).
考试技巧
Current = Voltage / Resistance. Remember: I = 120V / 80Ω = 1.5A. Divide voltage by resistance to find current.
记忆口诀
**I** = **1**20V / **8**0Ω = **1**.**5**A (think '120/80 = 1.5')
实际应用示例
You're testing a power amplifier. You apply 120 volts and measure 80 ohms resistance. Using I = E / R, you calculate the current: I = 120 / 80 = 1.5 amperes. This helps you verify the amplifier's operation and calculate power consumption.
错误选项分析
Option A: Incorrect. 9600 amperes would be multiplying voltage and resistance (120 × 80), which is mathematically incorrect. Current is voltage divided by resistance. Option B: Incorrect. 200 amperes would be adding voltage and resistance (120 + 80), which is mathematically invalid. Option C: Incorrect. 0.667 amperes would be dividing resistance by voltage (80 / 120), which is the inverse of the correct formula.
知识点
Ohm's Law calculation, Current calculation, I = E / R, Circuit analysis
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.