GED Science TestPhysical ScienceEasy
An electrician is installing a new light fixture. They connect a 120-volt power source to the fixture, which has a resistance of 20 ohms. What is the current flowing through the light fixture?
- A6 Amperes
- B240 Amperes
- C2400 Amperes
- D0.17 Amperes
Show answer & explanationAnswer & explanation
Correct answer: A. 6 Amperes
Ohm's Law states that current (I) equals voltage (V) divided by resistance (R). So, I = V/R = 120 V / 20 Ω = 6 A.
Why the other options are wrong
- B. This would be V * R, not V/R.
- C. This is an incorrect calculation; possibly 120 * 20 without decimal adjustment.
- D. This would be R/V, not V/R.
Ohm's Law
A fundamental law in electrical circuits stating that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them.
- Formula: V = I * R (Voltage = Current * Resistance).
- Can be rearranged to I = V/R or R = V/I.
- Applies to many materials, but not all (e.g., semiconductors).
Memory trick: VIR: Voltage Is Resistance times Current (V = I * R).