Q: The number of turns in a long solenoid is 500. The area of cross-section of solenoid is 2 × 10^{–3} m^{2} . If the value of magnetic induction, on passing a current of 2 amp, through it is 5 × 10^{–3} tesla, the magnitude of magnetic flux connected with it in weber will be

(A) 5 × 10^{–3}

(B) 10^{–2}

(C) 10^{–5}

(D) 2.5

Solution : Magnetic flux , $\displaystyle \phi = N B A$