Question

The linearity of the 11 k Ω variable resistor is 0.12% and the speed of the contact arm is 325°. This instrument is to be used as a potentiometer with a linear scale of 0 to 1.5 V. What will be the highest voltage error (in mV)?
1. 1.6
2. 1.5
3. 1.8
4. 0.8

Answer 1

Correct Answer - Option 3 : 1.8

Concept: When % of linearity is given it means that output is not varying directly proportionally to the input. It is somewhat showing deviation from linear relation.

Given,

Max rotation of rotating arm of variable resistor is given= 325^o

Linearity = 0.12% = \(\frac{0.12}{100}\)

So, deviation in displacement = 0.0012 × 325^o = 0.39^o

Maximum voltage that can be measure =1.5 V

It means 325^o displacement = 1.5 V

Hence, 0.39^o  displacement  = \(\frac{0.39}{325}×1.5\) = 0.0018 = 1.8 mV