Question

1.To determine the Young's modulus of a wire, the
formula is Y = x ; where L = length; A = area
of cross-section of the wire, AL = change in length
of the wire when stretched with a force F. The
conversion factor to change it from CGS to MKS
system is
(1) 1
(2) 10
(3)0.1
(4) 0.01
​

Answer 1

Young's modulus = stress/strain

we know, stress is the ratio of force applied and cross sectional area.

and strain is the ratio of change in length of wire to original length.

so, Young's modulus , Y = FL/A∆L

in MKS system , unit of Y is 1 N/m²

in C.G.S system, 1N = 10^5 Dyne

1 m² = (100cm)² = 10⁴ cm²

so, unit of Young's modulus in C.G.S system is (10^5 Dyne)/(10⁴ cm²)

= 10 Dyne/cm²

e.g., 1N/m² = 10Dyne/cm²

or, 1 Dyne/cm² = 0.1 N/m²

hence it is clear that conversion factor to change from c.g.s to mks system is 0.1

therefore option (3) is correct.