Question

A voltmeter has a least count of 0.1 V and an ammeter has a least count of 0.1 A. The potential drop V across a resistor is measured as 10.0 V and current through it is measured as 1.0 A. The value
of resistance with error is
(1) (10+1.1) ohm
(3) (10+0.5) ohm
(2) (1021) ohm
(4) (10+0.2) ohm​

Answer 1

Thus the value of resistance with error is R = ( 1.0 + 0.1 ) x 10

Option (A) is correct.

Explanation:

• ΔV = 0.1 V
• ΔI = 0.1 A
• v = 10.0 V
• I = 1.0 A

V = V + ΔV

I =  ( 1 + 0.1 )A

V = I R

R = V / I = 10 / 1 = 10 Ω

ΔR / R = ΔV / V + ΔI / I

ΔR / 10 = 0.1 / 10 + 0.1 / 1

ΔR  = 10 x  ( 0.01 + 0.1 ) ~ 0.1 x 10

R = ( 1.0 + 0.1 ) x 10

Thus the value of resistance with error is R = ( 1.0 + 0.1 ) x 10