Chapter 5: Electricity and Magnetism

Question 1

What is electricity?

Answer 1

The movement of electrons between atoms.

Question 2

What is the unit of electric charge?

Answer 2

Coulomb (C)

Question 3

What is the Law of Electrical Attraction and Repulsion?

Answer 3

Like charges repel, opposite charges attract.

Question 4

What is static electricity?

Answer 4

The transfer of electrons between objects at rest.

Question 5

What are three methods of charging?

Answer 5

Friction, Conduction, Induction

Question 6

What is an insulator?

Answer 6

A material that resists the flow of electric charge (high resistance).

Question 7

What is a conductor?

Answer 7

A material that allows electric charge to flow (low resistance).

Question 8

What is the electrostatic series?

Answer 8

A list showing how likely materials are to give or take electrons when rubbed together.

Question 9

What happens during conduction?

Answer 9

A charged object touches a neutral one → both end up with the same charge.

Question 10

What happens during induction?

Answer 10

A charged object is brought near (not touching) a neutral one → charges shift inside.

Question 11

What’s the difference between static and dynamic electricity?

Answer 11

Static = no current; Dynamic = flow of current in a circuit.

Question 12

What is electric current?

Answer 12

The flow of electric charge through a conductor.

Question 13

Symbol and unit for current?

Answer 13

I, measured in Amperes (A)

Question 14

Formula for current?

Answer 14

I = q / Δt (charge ÷ time)

Question 15

MATH Q: If 200 C of charge pass in 40 seconds, what is the current?

Answer 15

200 ÷ 40 = 5 A

Question 16

What is voltage (potential difference)?

Answer 16

The energy difference between two points in a circuit.

Question 17

Symbol and unit for voltage?

Answer 17

V, measured in Volts (V)

Question 18

Formula for voltage?

Answer 18

V = E / q (energy ÷ charge)

Question 19

MATH Q: If 600 J of energy move 300 C of charge, what is the voltage?

Answer 19

600 ÷ 300 = 2 V

Question 20

What is resistance?

Answer 20

The ability of a material to resist electric current.

Question 21

Symbol and unit for resistance?

Answer 21

R, measured in Ohms (Ω)

Question 22

What factors affect resistance?

Answer 22

1. Type of material
2. Length (longer = more resistance)
3. Diameter (thinner = more resistance)
4. Temperature (hotter = more resistance)

Question 23

Formula for Ohm’s Law?

Answer 23

V = I × R

Question 24

MATH Q: A toaster has 15 V and a current of 3 A. What is the resistance?

Answer 24

15 ÷ 3 = 5 Ω

Question 25

What is electrical power?

Answer 25

The amount of energy used per unit of time.

Question 26

Symbol and unit for power?

Answer 26

P, measured in Watts (W)

Question 27

Formula for power?

Answer 27

P = I × V

Question 28

MATH Q: If a device uses 120 V and 0.5 A, what’s the power?

Answer 28

120 × 0.5 = 60 W

Question 29

What is electrical energy?

Answer 29

The total energy consumed by an electrical device.

Question 30

Units of energy?

Answer 30

Joules (J) or kilowatt-hours (kWh)

Question 31

Conversion: 1 kWh = ?

Answer 31

3,600,000 J

Question 32

Formula for energy?

Answer 32

E = P × Δt

Question 33

MATH Q: A 100 W bulb runs for 2 hours. How much energy?

Answer 33

E = 100 × (2 × 3600) = **720,000 J**

Question 34

MATH Q: An electric heater runs at 1100 W for 3 hours/day for 30 days. Cost per kWh = $0.08. How much does it cost?

Answer 34

Total kWh = (1100 × 3 × 30) ÷ 1000 = 99 kWh Cost = 99 × 0.08 = **$7.92**

Question 35

In a series circuit, how do current and voltage behave?

Answer 35

Current = same throughout; Voltage = splits between components

Question 36

In a parallel circuit, how do current and voltage behave?

Answer 36

Voltage = same across each path; Current = splits between paths

Question 37

Series: Total resistance formula?

Answer 37

R_total = R₁ + R₂ + R₃...

Question 38

Parallel: Total resistance formula?

Answer 38

1/R_total = 1/R₁ + 1/R₂ + 1/R₃...

Question 39

What kind of circuit is used in houses?

Answer 39

Parallel (so if one device stops, the rest stay on)

Question 40

What is a magnet?

Answer 40

An object that produces a magnetic field and attracts iron, cobalt, or nickel.

Question 41

What are magnetic poles?

Answer 41

North and South → opposite poles attract, like poles repel.

Question 42

What are magnetic domains?

Answer 42

Tiny magnets inside materials → when aligned, they create a strong magnetic field.

Question 43

What is a magnetic field?

Answer 43

The invisible area of magnetic force around a magnet (from north to south).

Question 44

What happens when you break a magnet?

Answer 44

Each half becomes its own magnet with a north and south pole.

Question 45

What is Earth’s magnetic field called?

Answer 45

The magnetosphere.