Nelson Physics 12 - Chapter 8

What is a permanent magnet? (pt)

• A material that can easily be magnetized

• Produces its own magnetic field

• The magnetic field cannot be turned on and off

Magnetic Field Lines

A set of lines that are drawn to indicate the strength and direction of a magnetic field

What symbol is a magnetic field indicated by?

B

Where is the magnetic field the strongest and why?

At the poles because it is where the magnetic field lines are the closest together because they originate and terminate there

What are the differences between electric fields and magnetic fields?

Electric fields only need a single charge, but a magnetic field results from a magnetic dipole because there will always be either a north pole or a south pole

Magnetic lines always form ____ loops

Closed

Where do magnetic field lines in a bar magnetic go from?

North to South

In a bar magnetic, where is the magnetic field strength the strongest?

Between the gaps

What is a torque force?

Twisting force

What kind of force does the Earth’s magnetic field have on a compass needle?

A torque force

How many poles does Earth have? (pt)

• Geographic North Pole

• Magnetic North Pole (bottom)

• Geographic South Pole

• Magnetic South Pole (top)

Why do the poles keep moving on Earth?

Earth spins and causes the liquid metal in the core to change the magnetic fields

A magnetic field exerts a force on a charged particle ____ to the field and V of the particle

Perpendicular

What causes auroras?

Earth’s magnetic field deflects cosmic rays and they spiral downwards at the poles

Principle of Electromagnetism

Moving electric charges cause a magnetic field

RHR for a straight conductor

Right thumb in the direction of the conventional current, curled fingers are the direction of the magnetic field lines

What is a current loop?

A straight wire wounded

What rule do you use for a magnetic field of a current loop?

RHR for a straight conductor

Where are the field lines strongest in a current loop?

On the inside because of proximity, on the outside it is weaker

Solenoid

A conducting wire wounded into a loop

Where is the magnetic field the strongest in a solenoid?

In the middle because the field lines are the strongest in there

What happens to the magnetic field lines when a solenoid is tighter?

They are straighter and closer

What happens to the magnetic field lines when a solenoid is loser?

They are curvier and farther

RHR for a solenoid

Fingers are in the direction of the conventional current, right thumb is in the direction of the magnetic field lines

Where do the magnetic lines in a solenoid originate from and extend from

The center of the coil

What does turning the current in the wire of a solenoid do?

It can control the magnetic field of the solenoid

When the current is on in a solenoid, what does it turn into?

Electromagnet

What can a solenoid acting like an electromagnet do? (applications, pt)

• Scrap metal yards to pick up cars

• Washing machines

• MRI