Engineering Board Exam Reviewer · Ohm's Law · easy
A resistor draws 2 A from a 120 V source. If the source voltage falls by 10%, what current will flow (resistance unchanged)?
- 2.2 A
- 1.8 A
- 1.2 A
- 0.2 A
Answer
B. 1.8 A
Solution
R=120/2=60, . At 0.9×120=108 V: I=108/60=1.8 A. (Current is proportional to voltage, so a 10% drop in V gives a 10% drop in I.)
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