# Amplitude of the induced voltage across the coil

by lee.perrin@gm
Tags: induced voltage, inductance, magnetic field
 P: 8 If anyone can advise that would be great. 1. The plane of a 5 turn coil of 5mm² cross sectional area is rotating a 1200 r.p.m in a magnetic field of 10mT. Q. Calculate the amplitude of the induced voltage across the coil Data: 5 turns c = 1200 rpm A = 5cm² B = 10 mT 2. φ = N.B.A φ = 5×10×10^-3 ×5 × 10^-2 φ = 2.5 ×10^-3 V = dφ/dt or N.A. dB/dt The equation thought to have been used is the following but the Length is not vissible to me. V/L = c x B c being the speed B field L lenth of wire 3. I have tried two avenues please advise a: V(t) = -N•d(B•A)/dt = -N•B•dA/dt = N•B•ω•A•sin(ωt) V(t) =(5)(10x10^-3)(125.66370599999999)(5)sin(ωt) = 31.415 sin(ωt) volts. Or b: And using the following, saying t = 60 sec Then φ = N.B.A φ = 5×10×10^-3 ×5 × 10^-2 φ = 2.5 ×10^-3 And V = dφ/dt or N.A. dB/dt = 4.17x10^-3 V My concern here is that 1200rpm was not used.
Mentor
P: 37,560
 Quote by lee.perrin@gm If anyone can advise that would be great. 1. The plane of a 5 turn coil of 5mm² cross sectional area is rotating a 1200 r.p.m in a magnetic field of 10mT. Q. Calculate the amplitude of the induced voltage across the coil Data: 5 turns c = 1200 rpm A = 5cm² B = 10 mT 2. φ = N.B.A φ = 5×10×10^-3 ×5 × 10^-2 φ = 2.5 ×10^-3 V = dφ/dt or N.A. dB/dt The equation thought to have been used is the following but the Length is not vissible to me. V/L = c x B c being the speed B field L lenth of wire 3. I have tried two avenues please advise a: V(t) = -N•d(B•A)/dt = -N•B•dA/dt = N•B•ω•A•sin(ωt) V(t) =(5)(10x10^-3)(125.66370599999999)(5)sin(ωt) = 31.415 sin(ωt) volts. Or b: And using the following, saying t = 60 sec Then φ = N.B.A φ = 5×10×10^-3 ×5 × 10^-2 φ = 2.5 ×10^-3 And V = dφ/dt or N.A. dB/dt = 4.17x10^-3 V My concern here is that 1200rpm was not used.
You should write out the function φ(t) (hint: it is a sinusoidal function), then differentiate it to find V(t)...

 Related Discussions Electrical Engineering 2 Introductory Physics Homework 1 Introductory Physics Homework 1 Introductory Physics Homework 4 Introductory Physics Homework 2