A 500 $k \Omega$ potentiometer is connected across a 5 V source. If the voltage from the wiper to the lower end of the potentiometer is 1.2 V , what is the resistance of that lower part?
A) 120 $\mathrm { k } \Omega$
B) 380 $\mathrm { k } \Omega$
C) 0 $\Omega$
D) 500 $\mathrm { k } \Omega$

Question

A  500 $k \Omega$  potentiometer is connected across a  5 V  source. If the voltage from the wiper to the lower end of the potentiometer is  1.2 V , what is the resistance of that lower part?
A) 120 $\mathrm { k } \Omega$
B)  380 $\mathrm { k } \Omega$
C)  0 $\Omega$
D) 500 $\mathrm { k } \Omega$

Quizplus · Accepted Answer

The voltage across the entire potentiometer is 5V, and the voltage from the wiper to the lower end is 1.2V, which means the lower part of the potentiometer is taking up a fraction of the total voltage. The fraction is 1.2V/5V = 0.24. Since the total resistance is 500kΩ, the resistance of the lower part is 0.24 * 500kΩ = 120kΩ.

A 500 kΩk \OmegakΩ Potentiometer Is Connected Across a 5 V Source

A 500 $k \Omega$ Potentiometer Is Connected Across a 5 V Source