an ac electrical generator is made by turning a flat coil in a uniform constant
ID: 1455751 • Letter: A
Question
an ac electrical generator is made by turning a flat coil in a uniform constant magnetic field of 0.22 T. The coil consists of 33 square windings and each winding is 15.0 cm on each side. It rotates at a steady rate of 745 rpm about an axis perpendicular to the magnetic field passing through the middle of the coil and parallel to two of its opposite sides. An 8.5 ohm light bulb is connected across the generator. a) Find the voltage and current amplitudes for the light bulb. b) At what average rate is heat generated in the light bulb? c) How much energy is consumed by the light bulb every hour?
Explanation / Answer
flux = N*B*A*coswt
emf = rate of change in flux
emf = N*B*A*sinwt*w
maximum emf = N*B*A*w
voltage amplitude = 33*0.22*0.15^2*745*2*pi/60
voltage amplitude Emax = 12.74 V <<<<----answer
current amplitude, Imax = Emax/R= 1.5 A <<<<----answer
b)
power = I^2*R = 1.5^2*8.5 = 19.125 W
c)
E = P*t = 19.125*60*60 = 68850 J
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