Test 8: Electricity and Magnetism

Question 1

What is electricity?

Answer 1

A phenomena caused by positive and negative charges.

A form of energy most widely used to power machines of all kinds and your brain.

Question 2

What charges attract and repel?

Answer 2

Opposites attract (+  -)
Same charges repel (+  +)  (-  -)

Question 3

What is electrostatic electricity?

Answer 3

The study of phenomena related to electrical charges at rest.

Question 4

What charges can be transferred between two materials?

Answer 4

Negative charges (positive charges remain in place).

Question 5

What is a conductor?

Answer 5

It is a material or object that allows for the free flow of electrical charges.

Question 6

What is an insulator?

Answer 6

It is a material or object that impedes the free flow of electrical charges.

Question 7

What can electrons do?

Answer 7

• Leave or enter an object, creating a net charge on the object
• Move within an object that is a conductor, distributing charges within the object

Question 8

How does an object gain a charge?

Answer 8

• Friction (rubbing)
• Conduction (contact)
• Induction (approaching)

Question 9

What happens during friction?

Answer 9

• 2 neutral objects rub together
• Friction pulls the electrons away from one of the objects, transferring them to the other
• Now 2 objects of opposite charges

Question 10

What is electron affinity?

Answer 10

The direction the negative charges travel is determined by how strong each material is attracting them.

Question 11

What is an electrostatic series?

Answer 11

It is a list that ranks materials by their electron affinity (ability to gain or lose electrons)

Question 12

What happens during conduction?

Answer 12

• A charged object touches a neutral one
• The charge of one object will be shared between both objects
• Now 2 objects with the same charge

Question 13

What happens during induction?

Answer 13

• A charged object gets close to a neutral one
• The charged object will cause movement of charges in the neutral one
• Now one charged object and one dipole (uneven distribution of charges)
• A spark could occur when a charged object is brought really close to a dipole

Question 14

What is a coulomb?

Answer 14

The unit of measurement for an electrical charge.

Question 15

What does the force of 2 charged objects at rest depend on?

Answer 15

• The distance between the objects (inversely proportional)

- The amount of charge on each object (proportional)

Question 16

What is Fe and what is the unit?

Answer 16

• The force between the objects

- Newtons

Question 17

What is q1 +q2 and what is the unit?

Answer 17

• The amount of charge on the objects

- Coulomb

Question 18

What is r and what is the unit?

Answer 18

• The distance between the objects

- Metres

Question 19

What is k and what is the unit?

Answer 19

Constant of proportionality (Coulomb’s Constant)

k = 9 X 10^9 N m2 / C2

Question 20

How do we calculate the force of energy?

Answer 20

Fe = k q1 q2 / r2

Question 21

What is a force?

Answer 21

A push or pull that causes a change in motion.

Question 22

What is a force field?

Answer 22

The pattern in space of how force is felt by other objects.

Question 23

What is magnetism?

Answer 23

• The phenomena caused by magnets.

- A force like gravity or the and repulsion of electrostatic charges.

Question 24

What forms a magnetic field?

Answer 24

Electrons flowing in a magnet.

Question 25

What is a magnet?

Answer 25

An object that can attract other objects containing iron, nickel or cobalt.

Question 26

What materials are ferromagnetic?

Answer 26

• Iron
• Nickel
• Cobalt

Question 27

What do all magnets have?

Answer 27

• Two poles: north and south

- A north-seeking pole and a south-seeking pole

Question 28

Which poles attract and repel each other?

Answer 28

Opposites attract (S  N)
Same poles repel (S  S) (N  N)

Question 29

What is the relationship between the distance and magnetic force of the poles?

Answer 29

They are inversely proportional.

Question 30

Where are the geographic and magnetic poles on the Earth?

Answer 30

Geographic North and magnetic South are at the top.

Geographic South and magnetic North are at the bottom.

Question 31

Where does a compass point?

Answer 31

To the geographic North.

Question 32

What causes most of Earth’s magnetic field?

Answer 32

Moving molten iron in Earth’s outer core.

Question 33

What are 3 types of substances and describe them?

Answer 33

• Non-magnetic: not attracted or repelled by a magnet
• Magnetic: attracted or repelled by a magnet
• Ferromagnetic: attracted by a magnet, can be temporarily magnetized.

Question 34

What are magnetic fields?

Answer 34

• The space around a magnet where its field are felt.

Question 35

What can be used to determine the shape of a magnetic field?

Answer 35

Iron fillings.

Question 36

What can be used to determine the direction of the lines of force in a magnetic field?

Answer 36

A compass (North of compass points to South of magnet).

Question 37

What do field lines do of a magnetic field do?

Answer 37

• Converge at the poles
• Point away from North, towards South
• Never cross

Question 38

What is electromagnetism?

Answer 38

• Magnetization by electrical currents

- The interaction between electricity and magnetism

Question 39

How do you use the left hand rule?

Answer 39

• Left thumb points in the direction of electron current (points to positive)
• The fingers curl in the direction of the magnetic field lines.

Question 40

How do you use left hand rule for a solenoid?

Answer 40

• Start at negative
• Wrap your fingers under or over
• Thumb points to North

Question 41

What are some uses for solenoids?

Answer 41

• Magnetic crane
• Earphones/ speakers/ microphone
• Electric motor
• Electric doorbells