A resistance strain gauge with a gauge factor of 3 is fastened

A resistance strain gauge with a gauge factor of 3 is fastened to a steel member subjected to a stress of 100 N/mm². The modulus of elasticity of steel is approximately 2 × 10⁵ N/mm². The percentage change in resistance is ________

Gauge factor =	∇R/R
	ΔL/L

But	ΔL	=	100
	L		2 × 10⁵

∴	ΔR	=	3 × 100
	R		2 × 10⁵

∴ Percentage change =	∇R	× 100 = 0.15
	R