Question

Phys 20t 01-Spring 2019 Name: 1) A coil with N- 40 tums and radkus 3.0 em is placed in a region ot uniorm magnetic field perpendicular to the surface of the col The magnetic fieks changes from 0.0 T to 2.0 T in 0.80s a) Find the average emf induced in the col (12) R=5.0 Ω (5) b) Use Lenz's law and the right hand rue to find he drecton of the current in the resistor. Please explain. What is the magnitude of the current? Use e 0.4 V if you did not solve a) c) (4) pg. 1

Answer 1

Given N = 40 r = 3 cm = 3 times 10^- 2 m Delta B = B_2 - B_1 = 2 - 0 Delta B = 2T Delta T = 0.80 sec induced emf Vertical-bar e Vertical-bar = Vertical-bar - d phi/dt Vertical-bar = d/dt(N BA) Vertical-bar e Vertical-bar = NA dB/dt = NA Delta B/Delta t = N pi r^2 Delta B/Delta t Vertical-bar e Vertical-bar = 40 times 3.14 times (3 times 10^- 2)^2 times 2/0.80 = 2826 times 10^- 4 Vertical-bar e Vertical-bar = 0.2826 v since B uparrow with time, hence direction of induced current is anti clock wise which oppose the charge induced current I = epsilon/R = 0.2026/5 = 0.0565 A I = 56.5 mA