To measured a magnetic field between the magnetic poles of a loud speaker, a small coil having 30 turns and (2.5 ~cm ^2 ) area is placed perpendicular to the field and removed immediately. If the total charge flown through the coil is (75 10⁻³ C ) and the total resistance of wire and galvanometer is (0.3 ), then the magnitude of the magnetic field is

Step-by-step solution

Given, number of turns in the coil, (N=30 ) turns area of the coil, (A=2.5 ~cm ^2=2.5 10⁻⁴ ~m ^2 ) total charge flowing through the coil, (Q_ Net =7.5 10⁻³ C ) and total resistance of wire and galvanometer, (R=0.3 ) We know that, ( net charge, Q_ n e t = flux in the coil net Resistance ) ( Q_ net = R ) ...(i) We know that, flux ( = ) magnetic field ( ) area ( ) number of turns in the coil or ( =B N A ) ...(ii) Now, from Eqs. (i) and (ii), we get ( Q_ Net = B N A R ) Putting the given values, we get ( aligned 7.5 10