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A Level Physics Year 1 > Electricity > Flashcards

Flashcards in Electricity Deck (137)
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1

What is current?

It is the rate of flow of charge

2

Explain the water pipe analogy for current

The amount of water that flows depends on the flow rate and the time

3

What equation links charge, current and time?

Q = IT

4

What is the charge carried by in an electrical circuit?

Charge is carried through the wires by electrons

5

What is the unit of charge?

Coulombs

6

What is 1 coulomb defined as?

The amount of charge that passes in 1 second when the current is 1A

7

Do you attach an ammeter in series or in parallel in an electrical circuit?

Series

8

Why do you attach an ammeter in series?

So the current through the ammeter is the same as the current through the component

9

Which way does conventional current flow (in terms of + and -)?

+ve to -ve

10

Which way do electrons flow (in terms of + and -)?

-ve to +ve

11

Why do electrons flow from -ve to +ve?

Because electrons are negative, they are repelled by the negative and attracted to the positive

12

When a charge flows through a component, what does it do?

It transfers energy to the component

13

What do you need to do to make electrical charge flow through a circuit?

You need to transfer energy to the charge

14

Where does the energy needed to transfer energy to the charge come from?

A power source e.g. a battery

15

In a DC circuit, compare the speeds of the electrical current and the electrical energy

The electricity within the wires flows very slowly; at speeds around inches per minute. At the same time, the electrical energy flows at nearly the speed of light

16

What happens to the charge when it flows through the power source?

It is 'raised' through the potential (meaning it's voltage is raised) and energy is transferred to the charge as electrical energy

17

Explain how the power source does work?

It does work to move the charge around the circuit by transferring energy

18

What is potential difference?

The work done in moving a unit of charge between 2 points

19

What equation links potential difference, work done and charge?

V = W/Q

20

What is 1 volt equal to?

1 joule per coulomb

21

Explain, using the water analogy, potential difference

The p.d. is like the pressure that's forcing water along the pipe

22

Do you attach a voltmeter in series or parallel?

Parallel

23

Why do you attach a voltmeter in parallel?

Because it has a high internal resistance

24

Why do voltmeters have an almost infinite resistance?

So only a tiny current can flow through it because it only needs a small amount of current to measure the p.d.

25

What is resistance?

A measure of how difficult it is for current to flow

26

What is the p.d. and current if a component has a resistance of 1Ω?

A p.d. of 1V making a current of 1A flow through it

27

What equation links resistance, potential difference and current?

R = V/I

28

Who did most of the early work on resistance?

Georg Simon Ohm

29

What is Ohm's Law?

A rule to predict how the current would change as the potential difference is increased for certain types of conductor

30

What are ohmic conductors?

Conductors that obey Ohm's Law