electricity - electric charges and currents

Question 1

name some models of atoms in history

Answer 1

plum pudding model
Rutherford bohr model
charge cloud model
rutherford model

Question 2

what is an atom made up of

Answer 2

protons (positive charge)
neutrons (no charge)
electrons (negative charge)

Question 3

what do you need for an electric current to pass round a circuit?

Answer 3

• a complete circuit
• source of potential difference (battery)

Question 4

what is electric current

Answer 4

rate of flow of charge in wire

Question 5

what is the current due to?

Answer 5

passage of charged particles, called charge carriers

Question 6

_____ field in the ____ caused by _____ source _____ all _____ to move

Answer 6

electric field in wire caused by voltage source induces all electrons to move

Question 7

what is the convention of the direction of current

Answer 7

from positive terminal to negative

Question 8

symbol for charge

Answer 8

Q

Question 9

what are electrons in a circuit

Answer 9

Electrons are the charge carriers that flow in an electrical circuit – from the negative to positive terminals.

Question 10

unit for charge

Answer 10

coulombs C

Question 11

charge of proton (and electron)

Answer 11

1.6 x 10^19 C

Question 12

what is conservation of charge

Answer 12

no net electric charge can be created or destroyed

Question 13

what is electricity?

Answer 13

movement of charge around a circuit - electric current

Question 14

what is electric current

Answer 14

movement of negative charges (electrons) in a circuit

rate of flow of charge

Question 15

unit for current

Answer 15

ampere A

Question 16

symbol for current

Answer 16

I

Question 17

equation for current when there is a charge and time

Answer 17

Q = IT

Question 18

one amp of current is due to _______________________

Answer 18

a flow of charge of 1 couloumb per second

Question 19

what are 3 categories a material can be classified in electrical terms

Answer 19

conductors, insulators, semi-conductors

Question 20

what is an insulator?

Answer 20

each electron is attached to an atom and cant mov away.

when voltage is applied across insulator - no current passes through

as no electrons can move through

Question 21

what is a metallic conductor

Answer 21

most electrons are attached to atoms but some are delocalised (free to move)

delocalised electrons are charge carriers

when voltage is applied across metal, these conduction electrons are attracted to positive terminal

Question 22

what is a semi conductor

Answer 22

number of charge carriers increases with an increase in temperature

resistance of a semi conductor decreases as temperature is raised

Question 23

what makes a good conductor

Answer 23

allows electrons to move throw them easily

Question 24

what makes a good insulator

Answer 24

does not allow electrons to move easily

Question 25

what does a battery have potential to do?

Answer 25

potential to transfer energy

Question 26

what happens when a battery is in a circuit?

Answer 26

each electron passing through a circuit component does work to pass through the component and therefore transfers some/all of its energy

Question 27

work done by an electron is equal to….

Answer 27

The work done by an electron is equal to its loss of energy.

Question 28

what is work done per unit charge defined as?

Answer 28

potential difference

Question 29

what is potential difference?

Answer 29

Potential difference is defined as the work done (or energy transfer) per unit charge.

Question 30

what is the unit of pd

Answer 30

volt

Question 31

equation for p.d

Answer 31

V = W / Q

w - work done
q - charge

Question 32

what is the emf

Answer 32

The emf of a source of electricity is defined as the electrical energy produced per unit charge passing through the source.

Question 33

unit of emf

Answer 33

volt

Question 34

what is internal resistance

Answer 34

The resistance to the flow of charge within a source. Internal resistance results in energy being dissipated within the source.

Question 35

equation for work done by charge carriers

Answer 35

work done = IVt

current
pd
change in time

Question 36

equation for electrical power

Answer 36

P = IV
unit - watt

Question 37

what is one volt equal to

Answer 37

one volt is equal to one watt per amp