M4 Electricity & Magnetism

Question 1

attract

Answer 1

what two unlike charges do

Question 2

battery

Answer 2

the power source in a circuit made up of two or more cells

Question 3

break

Answer 3

an interruption in the flow of electricity

Question 4

cell

Answer 4

a single electrical energy source which uses chemical reactions to produce current

Question 5

circuit

Answer 5

a path through which electric current can flow

Question 6

closed circuit

Answer 6

an electric circuit through which current can flow without interruption

Question 7

Coulomb’s Law

Answer 7

the relationship between two charges
F =(1/4πε0_) x
(q1q2/r²)

Question 8

current

Answer 8

the flow of electric charge (q)
current unit is ampere (A)

Question 9

earth

Answer 9

the reference point from which voltages are measured

Question 10

electrical condutor

Answer 10

a material that allows electricity to flow through it eg metals

Question 11

electrical insulator

Answer 11

a material which does not allow electricity to flow through it eg wood

Question 12

electric permittivity constant

Answer 12

ε₀, epsilon naught, is the electric permittivity constant, that is the
permittivity of free space
= 8.854 x 10⁻¹² A²s⁴kg⁻¹m⁻³

Question 13

electricity

Answer 13

energy that comes from the flow of charged particles

Question 14

electromotive force

Answer 14

a source of energy that can cause a current to flow in an electrical circuit

Question 15

ferromagnetic

Answer 15

materials such as iron, cobalt and nickel that are more magnetic than other materials

Question 16

globe/bulb

Answer 16

an electrical component which lights up in a circuit

Question 17

leads

Answer 17

the wires used to join electrical componenets

Question 18

magnetic field

Answer 18

a region near a magnet where a force acts on magnetic materials

Question 19

mains electricity

Answer 19

electricity supplied for use in homes and businesses

Question 20

motor

Answer 20

an electrical component which rotates causing something to turn

Question 21

non-ohmic conductor

Answer 21

a conductor which does not obey Ohm’s law (a globe)

Question 22

Ohm’s Law

Answer 22

the relationship between voltage and current in an ohmic device
- V=IR

Question 23

ohmic conductor

Answer 23

a conductor which obeys Ohm’s Law

Question 24

open circuit

Answer 24

a break in a circuit

Question 25

parallel circuit

Answer 25

a circuit in which electric current flows through more than one series circuit

Question 26

permanent magnet

Answer 26

a magnet that creates its own permanent magnetic field

Question 27

permeability

Answer 27

a measure of the ability of a material to alter the magnetic field in the area that it is in

Question 28

potential difference (voltage)

Answer 28

the difference in potential between two points

Question 29

power source

Answer 29

a source of electrical power eg battery, mains etc

Question 30

repel

Answer 30

what two like charges do
- a force that pushes an object away

Question 31

series circuit

Answer 31

a simple circular path in which electric current flows only one way through each part

Question 32

solenoid

Answer 32

a cylindrical coil of wire which when current passes through it produces a magnetic field

Question 33

static electricity

Answer 33

the build-up of electrical charges on a surface eg rubbing shoes on carpet

Question 34

switch

Answer 34

a device which can control the flow of electricity

Question 35

symbol

Answer 35

a symbol used to represent an electrical component

Question 36

terminals

Answer 36

the parts of a battery that need to be connected in the circuit

Question 37

voltage

Answer 37

the amount of potential energy between two points on a circuit
- one point has more charge than another
- this difference in charge (between two points) is voltage

Question 38

TBCHANGED - QUESTION ABOUT HEAT IN ELECTRIC CURRENTS FROM TEST2

Answer 38

When an electric current passes through a metal, heat is produced as the ions in the metallic lattice vibrate with greater amplitude. This increases the chance of a collision of a free electron with an ion in the lattice.

Question 39

1 mA…?

Answer 39

milliamp, 1 x 10⁻³ A

Question 40

1 μA…?

Answer 40

microamp, 1 x 10⁻⁶ A

Question 41

Electric fields are represented by field lines that abide by…

Answer 41

• field lines never cross each other
• field liens are perpendicular to metal surfaces
• the direction of the field lines is given by the direction of the force acting on a proton (in the field)

Question 42

ammeters!

Answer 42

• go in series
• low resistance so it doesn’t add significant resistance to circuit

Question 43

voltmeters!

Answer 43

• parallel across a component
• high resistance so it doesn’t take significant current

Question 44

Across, Through Resistors?

Answer 44

voltage across a resistor
current through a resistor

Question 45

1 kΩ…?

Answer 45

kilo Ohm, 1000Ω

Question 46

1 MΩ…?

Answer 46

mega Ohm, 1 000 000Ω

Question 47

Kirchhoff’s Current Law

Answer 47

current in = current out

At any junction in a circuit, the sum of the currents arriving at the junction is the same as the sum of the currents leaving the junction (current is conserved)

• if this wasn’t the case, there would be a build up of electrons at that junction (creating charge from nothing) and that is impossible

Question 48

Kirchhoff’s Voltage Law

Answer 48

in any closed loop circuit, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop (which is also equal to 0)

Question 49

explain the right hand grip rule

Answer 49

• gives the direction of magnetic field

a dot is current out of page
a cross is current into page

thumb is direction of conventional current, direction of fingers is direction of magnetic field lines

Question 50

right hand coil rule

Answer 50

• gives the direction of a magnetic field due to the solenoid

fingers curl in direction of the current in the coil,
the thumb points in direction of North Pole (end of coil)