APP2 Magnetism IG

What is a ferromagnetic material?

• A material which is exhibits very strong magnetic effects.

• A material which is exhibits very weak magnetic effects.

• A material which is exhibits no magnetic effects.

Lines of the magnetic field produced by a long straight wire carrying a current are

• in the direction of the current

• opposite to the direction of the current

• outward from the wire

• inward toward the wire

• circles that are concentric with the wire

A wire in the plane of the page carries a current directed toward the top of the page as shown. If the wire is located in a uniform magnetic field B directed out of the page, the force on the wire resulting from the magnetic field is

• directed to the left

• directed out of the page

• directed to the right

• zero

The direction of the magnetic field at point R caused by the current I in the wire shown is

• to the left

• to the right

• into the page

• out of the page

In the cases shown below, the two parallel wires have the same magnitude current perpendicular to the plane of the page. The direction of the current in each wire is shown. Rank the magnitude of the net magnetic field at point P.

• B > A > C > D

• D > B > C > A

• B > D > A > C

• A > D > C > B

Which of the following is true about field lines? (Select all that apply)

• They go from a north magnetic pole to a south magnetic pole

• They go from a south magnetic pole to a north magnetic pole

• Their spacing shows the strength of the field

• They cannot cross

Answer explanation

Just like for electric fields, magnetic field lines allow us to represent the features of a magnetic field. Their spacing and direction indicate the strength and direction of the field and they start at the north magnetic pole and end at the south magnetic pole (never crossing!).

How does a magnetic field affect a moving electric charge?

• It doesn't

• It exerts a force parallel to the velocity of the charge and parallel to the direction of the field

• It exerts a force perpendicular to the velocity of the charge and parallel to the direction of the field

• It exerts a force perpendicular to the velocity and perpendicular to the direction of the field

Answer explanation

Remember your right hand rule! The velocity the charge, the direction of the field, and the force the charge experiences are all perpendicular to each other.

How does a magnetic field affect a stationary electric charge?

• It doesn't

• It exerts a force parallel to the velocity of the charge and parallel to the direction of the field

• It exerts a force perpendicular to the velocity of the charge and parallel to the direction of the field

• It exerts a force perpendicular to the velocity and perpendicular to the direction of the field

Answer explanation

A magnetic fields only exert a force on a moving electric charge.

True or false: every magnet is a dipole.

• True

• False

Answer explanation

A magnet will always have a north pole and a south pole; 2 poles = dipole.

Which image represents a magnetic field out of the page, and a charged particle moving to the left?

• Left

• Middle

• Right

Answer explanation

Right-hand rule!