MHT CET202014 Oct 2020Evening ShiftPhysicsMechanical Properties of SolidsActual
A metal sphere of radius 1 ~m is charged with 10⁻² C in air. Its bulk modulus is 10¹¹ / 4 ² . The volume strain in the sphere is ( ₀= . pemittivity of free space)
Options
- A10⁻¹ 6 ₀
- B10⁻¹⁴ 8 ₀
- C10⁻¹⁵ 8 ₀
- D10⁻¹² 4 ₀
Correct answer
C. 10⁻¹⁵ 8 ₀
Step-by-step solution
surface charge density = q 4 r² = 10⁻² 4 1 = 10⁻² 4 C / m ² strain = F A = 1 2 ² ₂ = 1 2 ₀ ( 10⁻² 4 )²= 10⁻⁴ 32 ² ₀ strain = stress k = 1 2 ² ₀ k where k= 10¹¹ 4 ² substituting and calculating we get strain = 10⁻¹⁵ 8 ₀