Physics question-electromagnetic induction

[Eric's collar]

I came across a question that I didn't understand when going through past papers so I thought someone on here might be able to explain it. It's not homework.



This is a terrible attempt at the diagram. Basically there are supposed to be coils. Forgot a switch but you should get the idea.

1) When the switch is turned on, what would you see on the ammeter.

A- Deflection then back to 0
B- Steady deflection
C- No deflection

2) When the switch is turned off what would you see on the ammeter immediately after switching it off

3) There was a seprate diagram for this but, what would you see if a bar magnet was placed at the ammeter whilst it is stationary.

My thoughts are
1) A
2) A
3) C

Because it's a cell and it is d.c., does that mean that deflection on the ammeter will not be steady as d.c. only goes in one direction whereas in a.c it is constantly changing therefore deflection will only be steady in a.c.

 

[meghatronic]

Well only a change in the magnetic field will induce a current.....

 

[Eric's collar]

I know that it needs to cut the fields as such so would turing the switch on do that?

 

[meghatronic]

I know that it needs to cut the fields as such so would turing the switch on do that?

Well is there going to be any change in the magnetic field with a DC current?

 

[Eric's collar]

I'm pretty sure it does for a very short time then goes back to 0.

 

[Six7th]

As the switch is closed, you get a change in magnetic field in the coil which then induces a current in the adjacent circuit. When this change stops the current is no longer induced and the ammeter will read 0. When the switched is turned off, the emf induced will try to oppose this change and cause the ammeter to read a current which will then go to 0.

So I would say AAC aswell. Could be wrong though!

 

[Shadez]

if its like the diagram you showed. nothing! as the coils are to far apart and wont share a magnetic field.

so CCC

 

[Shadez]

As the switch is closed, you get a change in magnetic field in the coil which then induces a current in the adjacent circuit. When this change stops the current is no longer induced and the ammeter will read 0. When the switched is turned off, the emf induced will try to oppose this change and cause the ammeter to read a current which will then go to 0.

So I would say AAC aswell. Could be wrong though!

correct!

just re read the question and it could be AAB, it all depends on how the bar magnet reacts with the ammeter it could be a old meter with a steal/ iron parts that could be effected by the magnet.

 

[FluffySheep]

A
A
C

AFAIK

(enough letters for you???

 

[Makhaira]

AAC