A 20 foot length of two-conductor 26 AWG copper wire is used to connect a single strain gage into a quarter-bridge circuit. If each conductor has a resistance of 20.4 Ω per 1000 feet, how much has the apparent gage resistance changed? Calculate the strain induced by this error if the initial gage resistance is 120 Ω and 350 Ω.

the error in conductor 1 (120 Ω) is 0.33%

the error in conductor 2 (350 Ω) is 0.11%

meanwhile, the current is constant.

Explanation:

Given:

initial gage resistance = 120 Ω and 350 Ω

conductor = 26 AWG

resistance = 20.4 Ω and 1000 feet

if 20 feet length of two conductor, each conductor has a resistance equal to

(20.4/1000 ft) Ω

the change in resistance in conductor is equal to

(20 * 20) / 1000 = 400/1000

thus the error is 0.4 Ω

the error in conductor 1 (120 Ω) is

(0.4/120) * 100 = 0.33%

the error in conductor 2 (350 Ω) is

(0.4/350) * 100 = 0.11%

meanwhile, the current is constant.