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This is chapter 21, problem number 86.
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We are asked to calculate the ratio, the rate of change in magnetic field, given the number of turns in a coil, has 35, and the diameter of the coil is 12 .5 centimeters.
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So that would be 12 .1 times 10 .5 meters.
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And the emf induced is 120 volts.
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In order to calculate the n .o .d., we need to remember the induced emf equals to negative of change of flux with respect to time.
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So here, our flux is obviously, we're talking about a coil here, so it's going to be b times a times and number of turns.
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If you're calculating the magnitude, then we're going to drop that negative sign, right? the magnitude of the emf, then is going to be equal to delta phi over delta t.
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Then is going to be equal to plug in for flux and times b times a.
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Now, number of turns is not changing with perspective time, and the area is not changing with respect to time...