PH 202

Quiz # 06 (10 pts)

Name

Solution

 

Consider the situation above of the bar magnet being moved closer to the coil shown.  The current induced in the coil, at the top of the coil, will be directed towards…

 

A.

Into the paper

B.

Out of the paper

C.

No current will be induced

 

 

 

 

 

Since the B field will be directed to the right and growing stronger, the induced B field needs to be directed to the left to oppose the change in the magnetic flux.  To create a B field directed to the left, the current must go into the paper at the top and come out of the paper at the bottom of the coil using the right hand rule!

 

So Correct Answer is A !

 

An Indy car has a bumper that is  wide.  The car is traveling at a speed of  going due East.  The vertical component of the Earth’s magnetic field at this location is  and is directed down into the Earth.  What is the potential difference between the north side and the south side of bumper that develops because of the moving metal in a magnetic field?  A positive potential difference means the north side is higher in potential than the south side.

 

A.

B.

C.

 

D.

 

 

 

Magnetic force is given by

So resolving the cross product

 

So positive charges are pushed North, so the emf induced relative to north is

 

 

So Correct Answer is B !

 

A metal bar  long is moving to the left at .  There is an applied magnetic field directed into the paper as shown with a field strength of .  The light bulb is a standard incandescent bulb with an operating resistance of .  What is the direction and magnitude of the current induced in the conducting rails?

 

A.

C.

 

 

 

 

B.

D.

 

And

By the right hand rule, the positive end of the bar will be the bottom, so the current will go clockwise!

Combining equations

 

 

 

 

So Correct Answer is C !

 

A coil, which has  induced across it when the magnetic flux changes by  over a period of .  How many turns does this coil possess?

 

A.

10

B.

2.5

C.

4000

 

D.

160

 

 

Faraday’s law gives us

Solve for N

 

 

So the Correct Answer is A !

 

A square coil is  along each side.  It also has 100 turns of wire around it.  It is oriented within a uniform magnetic field as shown on the right.  The angle indicated is  and the magnetic field strength  directed to the right as shown.  What is the magnetic flux passing through the coil?

 

A.

C.

 

 

 

 

B.

D.

 

The magnetic flux is found from

 

Below the geometry of what  is as it must be the angle between the normal to the plane of the coil and the direction of the magnetic field.

So the magnetic flux is

 

 

 

So Correct answer is D !

 

 

 

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This page last updated on October 9, 2020