What formula is used to calculate current in a circuit?
The correct answer is B: I = E / R. The formula used to calculate current in a circuit is I = E / R, where I is current in amperes, E is voltage in volts, and R is resistance in ohms. This is Ohm's Law.
Ohm's Law is one of the most fundamental electrical formulas: Current equals Voltage divided by Resistance. This formula allows you to calculate current when you know voltage and resistance. For example, if you have 12 volts across a 6-ohm resistor, current = 12 V / 6 Ω = 2 amperes. Ohm's Law is essential for understanding and designing electrical circuits. It's one of the most important formulas to memorize for amateur radio.
Exam Tip
Ohm's Law = I = E / R. Remember: Current equals voltage divided by resistance. This is Ohm's Law, one of the most important electrical formulas.
Memory Aid
"**I** = **E** / **R** (think 'IER' = I equals E divided by R, Ohm's Law)"
Real-World Application
You have a 12-volt battery connected to a circuit with 4 ohms of resistance. Using Ohm's Law: I = E / R = 12 V / 4 Ω = 3 amperes. This tells you 3 amperes of current will flow through the circuit. This formula is essential for understanding how circuits work and calculating current in any DC circuit.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. I = E × R would give you voltage squared divided by resistance, not current. Current is voltage divided by resistance, not multiplied.
Option C: Incorrect. I = E + R doesn't make sense mathematically. You can't add voltage and resistance to get current.
Option D: Incorrect. I = E - R doesn't make sense mathematically. You can't subtract resistance from voltage to get current.
题目解析
The correct answer is B: I = E / R. The formula used to calculate current in a circuit is I = E / R, where I is current in amperes, E is voltage in volts, and R is resistance in ohms. This is Ohm's Law. Ohm's Law is one of the most fundamental electrical formulas: Current equals Voltage divided by Resistance. This formula allows you to calculate current when you know voltage and resistance. For example, if you have 12 volts across a 6-ohm resistor, current = 12 V / 6 Ω = 2 amperes. Ohm's Law is essential for understanding and designing electrical circuits. It's one of the most important formulas to memorize for amateur radio.
考试技巧
Ohm's Law = I = E / R. Remember: Current equals voltage divided by resistance. This is Ohm's Law, one of the most important electrical formulas.
记忆口诀
**I** = **E** / **R** (think 'IER' = I equals E divided by R, Ohm's Law)
实际应用示例
You have a 12-volt battery connected to a circuit with 4 ohms of resistance. Using Ohm's Law: I = E / R = 12 V / 4 Ω = 3 amperes. This tells you 3 amperes of current will flow through the circuit. This formula is essential for understanding how circuits work and calculating current in any DC circuit.
错误选项分析
Option A: Incorrect. I = E × R would give you voltage squared divided by resistance, not current. Current is voltage divided by resistance, not multiplied. Option C: Incorrect. I = E + R doesn't make sense mathematically. You can't add voltage and resistance to get current. Option D: Incorrect. I = E - R doesn't make sense mathematically. You can't subtract resistance from voltage to get current.
知识点
Ohm's Law, I = E / R, Current calculation, Electrical formulas
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.