A generator gives e = e₀sinω t, with e₀ = 170 V and f = 60 Hz…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A generator gives , with V and Hz. The emf is zero at and rising. Find the emf at ms, and the first time at which the emf reaches V.
Need a reminder? The key ideaShow
A coil of turns and area turning at angular speed in a field has , with the peak emf and . The mechanical power that turns it equals the electrical power, . The average power in a resistor is .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. V, Hz, so .
Step 1. At ms. The angle is . Then .
Step 2. The first time at V. We want , so . The first angle with this sine is rad. So .
Answer: V, and ms.
Check. One cycle lasts ms. The peak comes at a quarter of that, about ms. The emf is V at ms and reaches V a little earlier, both before the peak, as it should.
What if? The emf also reaches V on the way down, after the peak, at ms. The sine has two angles for each value in the first half cycle.
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