(i) When current passes through a solenoid it behaves like a (a) Toroid (b) Circular magnet (c) Horse shoe magnet (d) Bar magnet

Question

A coil of many turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid. When current passes through it it behaves like a magnet. The diagram of magnetic field lines produced by the solenoid is given below

(i) When current passes through a solenoid it behaves like a 

(a) Toroid 

(b) Circular magnet 

(c) Horse shoe magnet 

(d) Bar magnet 

(ii) What is the strength of the magnetic field inside the solenoid when current passes through it . 

(a) μ₀nI 

(b) μ₀nI/2 

(c) μ₀nI² 

(d) 2μ₀nI 

(iii) Find out the ratio of the magnetic field inside a toroid and a solenoid,when same current passes through them having the same number of turns per unit length. 

(a) 1:1 

(b) 1:2 

(c) 2:1 

(d) 4:1 

(iv) Find out the strength magnetic field, when the air core solenoid is replaced by soft iron.

(a) μ₀μ_rnI 

(b) μ₀μ_rnI/2 

(c) 2μ₀μ_rnI 

(d) 1/3μ₀μ_rnI 

(v) On which factor does the magnetic north and South Pole produced in a solenoid depend? 

(a) direction of current 

(b) Number of turns per unit length 

(c) Number of turns. 

(d) Magnitude and direction of current

Answer 1

(i)  (d) Bar magnet

(ii)  (a) μ₀nI 

(iii) (a) 1:1 

(iv)  (a) μ₀μ_rnI 

(v)  (a) direction of current