a) A moving coil is very sensitive device to measure very small current. i) Define voltage sensitivity of moving coil galvanometer. On which factors…

a) A moving coil is very sensitive device to measure very small current.

i) Define voltage sensitivity of moving coil galvanometer. On which factors does it depend? 

ii) Why is magnetic field made radial in a moving coil galvanometer? 

b) State Faraday's laws of electromagnetic induction. The magnetic flux passing perpendicular to the plane of a coil is given by \( \phi = 4t^2 + 5t + 2 \), where \( \phi \)is in weber and t is in seconds. Calculate the magnitude of instantaneous emf induced in the coil when t = 3s. 

c) Derive an expression for energy stored in an inductor. 

                  OR

a) Obtain an expression for magnetic field strength at the centre of current carrying circular coil using Biot-Savart's law.

 b) A slice of indium antimonide 2.5 mm thick carries a current of 150 A. A magnetic field of flux density 0.5T, correctly applied, produces a maximum Hall voltage of 8.75  mV between the edges of the slice. Calculate the number of free charge carriers per unit volume assuming they each have a charge of \( -1.6 \times 10^{-19}\text{C} \) 

c) Derive an expression for the force exerted per unit length between two parallel current carrying conductors if currents are flowing in the same direction. Hence, define one ampere current.