CSLB C-10 Electrical ContractorElectrical Theory and CalculationsEasy
An electrician is troubleshooting a circuit and measures a voltage of 240V across a component and a current of 5A flowing through it. What is the resistance of the component?
- A24 ohms
- B48 ohms
- C1200 ohms
- D0.02 ohms
Show answer & explanationAnswer & explanation
Correct answer: B. 48 ohms
According to Ohm's Law, Resistance (R) = Voltage (V) / Current (I). So, R = 240V / 5A = 48 ohms.
Why the other options are wrong
- A. This results from dividing current by voltage (I/V), which is incorrect.
- C. This would be the power (P = V * I), not resistance.
- D. This is the reciprocal of 48 (1/48), indicating an inverted Ohm's Law application.
Ohm's Law (Resistance)
Ohm's Law states that resistance (R) is equal to voltage (V) divided by current (I), expressed as R = V/I.
- Resistance is measured in ohms (Ω).
- Voltage is measured in volts (V).
- Current is measured in amperes (A).
- This fundamental law relates voltage, current, and resistance in DC circuits and resistive AC circuits.
Memory trick: V over I times R, the Ohm's Law, is clear.