Magnetic Forces and Electrictromagnetism

Magnetic and Electric Forces

What is a Magnet?

• Magnets are any material that attracts iron and materials that contain iron

• Magnets attract or repel other magnets

• One end of a magnet will always point north when allowed to swing freely

How do Magnetic Poles Interact?

• All magnets have two ends called magnetic poles

• The pole of the magnet that points north is called the north pole. The one that points south is the south pole.

• Unlike Poles attract

• Similar poles repel

• The poles have the strongest magnetic effect

Multiple Choice

A positive charge and a positive charge will _______.

• Attract 
• Repel

Multiple Choice

A negative charge and a positive charge will ________.

• Attract
• Repel

Multiple Choice

The part of the magnet with the strongest attraction and is labeled N and S is called magnetic __________.

• poles 
• attractor
• repel
• compass

Multiple Choice

Any material that exerts magnetic force is considered a magnet

• True

• False

Multiple Choice

Like all other forces, a magnetic force is a(n) gravitational force

• True

• False it is actually a push or pull

• False it is actually a Potential Force

Multiple Choice

When freely swinging, one end of the magnet always points east

• True

• False, it points north

• False it points west

• False it points randomly

What is a Magnetic Field's Shape?

• Magnetic force is strongest at the poles but not limited to the poles

• The area of magnetic force around a magnet is known as its magnetic field

• Because of magnetic fields, magnets can interact without even touching

• Magnetic field lines spread out from one pole, curve around the magnet, and return to the other pole

• Magnetic field lines will always leave the north pole and enter the south pole

• The closer the lines are, the stronger the field

• Magnetic field lines are closest together at the poles

What is Earth's Magnetic Field Like?

• A compass is a device that has a magnet on a needle that spins freely. The needle points north.

• Just like a bar magnet, Earth has a magnetic field around it and two magnetic poles.

• The poles of a magnetized compass needle align with Earth's magnetic Field

• 
  

Earth's Core

• Earth's core is a large sphere of metal at Earth's center

• The outer core is made of hot swirling liquid iron

• The motion of this iron creates a magnetic field similar to the magnetic field of a bar magnet

• 
  

Multiple Choice

Magnetic field lines are closest together...

• near the center of the magnet

• At the magnet's poles

• North pole only

• South pole only

Multiple Choice

A _________ is a particle with a positive charge.

• Neutron
• Electron
• Proton

Multiple Choice

This tool is a ___________.

• Compass
• Pole
• Star
• GPS

Electromagnetic Force

• Magnets have magnetic fields...BUT an electric current can also produce a magnetic field!

• Whenever there is electricity, there is magnetism

• An electric current produces a magnetic field

• This relationship is called electromagnetism

Electric Current

• The circuit must be closed for electric current to flow

• If the circuit is open, the current cannot flow

• 
  

• 
  

What is a Magnetic Field Produced by a Current Like?

• The magnetic field produced by a current has a strength and a direction.

• The field can be turned on or off, have its direction reversed, or have its strength changed

Change the Strength of a Magnetic Field

• Increase the amount of current in the wire (battery strength)

• Increase your loops in your wire!

• The magnetic field around the wire forms a CIRCLE. When you make a loop in a wire, this causes the magnetic field lines to bunch closer together

• Magnetic forces increase when magnetic field lines are closer together

Multiple Choice

When electrons flow through wires from a - terminal to a + terminal a/an ___________ is created.

• Flow

• Electromagnet

• Current

• Magnet

Multiple Choice

The magnetic field of a magnet is ____________ further away from the magnet.

• Smaller

• Stroner

• Larger

• Weaker

Multiple Choice

What forces works only by combining electric and magnetic forces?

• electric

• magnetic

• static electricity

• electromagnet

Multiple Choice

The battery is the ________ of energy.

• Wire 
• Source 
• Insulator
• Negative

Multiple Choice

Is this an open circuit or a closed circuit?

• Open 
• Closed

Multiple Choice

Is this an open circuit or a closed circuit?

• Open 
• Close

Multiple Choice

Which object could replace the penny and the light bulb would still light up?

• Crayon
• Toothpick
• Rubberband
• Paperclip

Multiple Choice

An electric ________ produces a magnetic field.

• Battery

• Magnet

• Current

• Circuit