MHT CET202016 Oct 2020Evening ShiftPhysicsMagnetic Effects of CurrentActual
The length of solenoid is ' 'whose windings are made of material of density 'D' and resistivity ' 0^ . The winding resistance is 'R'. The inductance of solenoid is ( m = . mass of winding wire, ₀= permeability of free space)
Options
- A₀ 2 ( R m Q D )
- B₀ 4 ( R m Q D )
- C₀ 2 ( D Rm )
- D₀ 4 ( Q D Rm )
Correct answer
B. ₀ 4 ( R m Q D )
Step-by-step solution
(D) We know, L = ₀ ~N ² A If x is the length of the wire and a is the area of cross section R = x a m = axD Rm = x a axD x = Rm D Also, x=2 r N N= X 2 = ₀ ( x 2 r )² r ² = ₀ 4 Rm pD