Magnetic Field and Force

Are the magnetic field lines in the picture correct?

• Yes, because they point from north to south.

• No, because they point from north to south (they're supposed to go the other way).

• Yes, because the North pole is on the left in all pictures.

• No, because the North pole is on the left in all pictures (it's supposed to be on the right).

The strongest part of a magnet is...

• the bars .

• the force field.

• the poles.

• the middle.

In this image, matching north poles from two magnets are introduced.  What do you predict will be the outcome?

• There will be no interaction.  The poles of magnets do not have an effect on one another.
• The two north poles will attract each other
• The two north poles will repel each other
• The two magnets will combine and become one magnet

Looking at the field lines in this picture, these two magnets are ________

• Attracting

• Repelling

• Attracting and Repelling

• Doing nothing

A wire carries a current, creating a magnetic field around itself as shown. The current in the wire is:

• Directed to the right

• Directed to the left

• Equal to the magnetic field

• In the same direction as the magnetic field

The SI unit of magnetic field strength is the

• watt

• tesla

• coulomb

• newton

An electric charge, q, moves with a constant velocity, v, PARALLEL to the lines of force of a uniform magnetic field, B. The force experienced by the charge is

• Bqv

• zero

An electric current 𝐼 passes through a wire with a semicircular section of radius 𝑎 as shown below. What is the direction of the magnetic field at the point P?

• Out of the page

• Into the page

• upward

• downward

Two long, parallel wires each carry the same current 𝐼 in the same direction. What is the total magnetic field at the point 𝑃 midway between the wires?

• Zero

• Directed into the page

• Directed out of the page

• Directed to the left

What happens when two north poles of a magnet are placed together?

• they repel
• they attract
• they cancel each other out
• the strength of the magnet is doubled