Lorentz’s law of voltage for ac-generator

[loki4000]

Homework Statement

Greetings
So i was trying to solve following prolems:

Homework Equations

The Attempt at a Solution

I did manage to solve problem 22 using
E = NAB(2pi * f)
E = (100)(0.005)(0.9)(2pi)(50) = 141.372 v

But I have no idea what to do with problem 21. Mostly because I don't know what Lorentz’s law of voltage is.
I am aware that there is law for lorenz Force, but it require stuff like length, drift velocity and other data not given in problem. Not to mention that I do not need Force, I need Voltage.

 

[Simon Bridge]

I don't know what Lorentz’s law of voltage is.

I suspect the author has made a typo. Could he be referring to Lenz's Law?

 

[loki4000]

I suspect the author has made a typo. Could he be referring to Lenz's Law?

I don't know. I suppose that is possible, since I never heard before about Lorentz’s law of voltage.

 

[Simon Bridge]

Does the question come from a textbook?

 

[loki4000]

Does the question come from a textbook?

No, just screensot from unknown book our lecturer send us before goin to easter holiday. No details,sadly.

Anyway, since google does not find anying about Lorentz’s law of voltage it can indeed be a typo. However, from what I can see, Lenz's Law = E=-N (dФ/dt) or emf = -(loopsofwire)(magnetic flow over some area, per time).
This is looking fairly similar to my solution or problem 22. And, from my understanding, Lenz's Law is part of Faraday law.
So I guess I already solve it using Lenz's Law in problem 22, it's problem 21 that confuse me.