GED Science TestPhysical ScienceMedium
An electrical engineer is designing a circuit and needs to select a resistor. The resistor has a voltage drop of 12 V across it, and a current of 0.5 A flows through it. What is the resistance of the resistor?
- A0.042 Ω
- B6 Ω
- C24 Ω
- D12.5 Ω
Show answer & explanationAnswer & explanation
Correct answer: C. 24 Ω
According to Ohm's Law, Voltage (V) = Current (I) × Resistance (R). To find resistance, rearrange the formula to R = V/I. So, R = 12 V / 0.5 A = 24 Ω.
Why the other options are wrong
- A. This is current divided by voltage (0.5/12), which is incorrect.
- B. This is voltage multiplied by current (12 * 0.5), which calculates power, not resistance.
- D. This is an arithmetic error or incorrect formula application.
Ohm's Law
Ohm's Law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points, and inversely proportional to the resistance between them. It is expressed as V = IR.
- V = IR (Voltage = Current × Resistance)
- Units: Voltage in Volts (V), Current in Amperes (A), Resistance in Ohms (Ω)
- Applies to ohmic materials
Memory trick: Ohm's V-I-R triangle