# Homework Help on Kirchoff's Laws and Magnetic Induction

1. Mar 30, 2015

### Dhooy7

1. The problem statement, all variables and given/known data
I am stuck on 2 and 3.

I attached all the problems and variable and unknowns

2. Relevant equations

I attached my work for 1, 2, and 3. I'm not sure if it is right though.

3. The attempt at a solution

Can someone check my work for problems 1, 2, 3 and 4?

The equations, attempts and relevant information is attached!

I'm stuck on 4-13 but have no answers or don't know where to start

#### Attached Files:

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• ###### hw 8 physics.pdf
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2. Mar 30, 2015

### gracy

In second problem of your attached pdf ,unit of magnetic flux is given to be tesla,it is incorrect.It should be Wb.
Then the problem becomes easy.Just apply faraday's law of electromagnetic induction.
One more thing ,in faraday's law make sure you have included number of loops.

Last edited: Mar 30, 2015
3. Mar 30, 2015

### Dhooy7

gracy, I am confused because the problem says 0.04T to 0.3 T. What do you mean the answer should be in Webers?

4. Mar 30, 2015

### gracy

5. Mar 30, 2015

### Dhooy7

What do you mean second Question? . From hw 8, I am looking at problem 2.

6. Mar 30, 2015

### gracy

Yes ,I am talking about that only.

7. Mar 30, 2015

### Dhooy7

So it should be 0.26 Webers? Or are you saying I need to convert that to webeters to use it in the emf equation?

8. Mar 30, 2015

### gracy

Ok.Just look at faraday's law f electromagnetic induction,and tell me it has magnetic flux or magnetic field?

9. Mar 30, 2015

### Hesch

In problem 1, you can use fewer equations: Naming the loop currents L1 and L2, they must be:

Loop 1: 8V - L1*50Ω - 10V - L1*200Ω + L2*200Ω = 0
Loop 2: 40V - L2*200Ω + L1*200Ω + 10V= 0

The voltage change over R3 is caused by both L1 and L2 as they both pass R3.

Having solved L1 and L2, you can easily calculate I1 = L1, I2 = L2, I3 = L1 - L2

10. Mar 30, 2015

### Dhooy7

magnetic flux.

11. Mar 30, 2015

### gracy

Good.What is the unit of flux?

12. Mar 30, 2015

### Dhooy7

I guess I don't understand where you are going with this.

13. Mar 30, 2015

### Dhooy7

In the book it uses m^2T

14. Mar 30, 2015

### gracy

For what?

15. Mar 30, 2015

### Dhooy7

magnetic flux.

16. Mar 30, 2015

### gracy

Yes.Actually magnetic flux SI unit is Weber (symbol Wb)And one weber per square metre is one tesla(T)
I hope you now understand what is wrong with the problem 2 of hw 8,

17. Mar 30, 2015

### Dhooy7

It's the units for flux to use

18. Mar 30, 2015

### Dhooy7

Did I do 3 and 1 correctly?

19. Mar 30, 2015

### Dhooy7

Can anyone give me assistance on 4-13 on how to start. I've looked in my book several times.

20. Mar 31, 2015