Electricity Flashcards

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1
Q

From which end of a cell does the electric current flow from and to?

A

From the POSITIVE end of the cell TO the NEGATIVE end (known as conventional current).

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2
Q

What is a series circuit?

A

A circuit that has NO BRANCHES and the CURRENT can only flow in ONE PATH.

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3
Q

What is key about current in series circuit?

A

The CURRENT is the SAME all the way around a series circuit.

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4
Q

What is key about current in parallel circuits?

A

The CURRENT in the branches ADDS UP to the TOTAL CURRENT leaving the cell.

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5
Q

What is meant by potential difference (voltage)?

A

A potential difference of 1 volt tells us that 1 JOULE of energy is TRANSFERRED for EACH COULOMB OF CHARGE that is moving through the circuit.

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6
Q

What is key about potential difference in parallel circuits?

A

The potential difference across each COMPONENT is the SAME.

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7
Q

What is key about potential difference in series circuits?

A
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8
Q

What equation do you use to calculate charge flow?

A

charge flow (C) = current x time Q = I x t

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9
Q

What equation do you use to calculate energy transfer?

A

energy transferred = charge flow x potential difference E = QV

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10
Q

What is meant by resistance in circuits?

A

Tells us the potential difference required to drive a current through a component.

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11
Q

aWhat equation do you use to calculate resistance?

A

resistance (Ω) = potential difference / current R = V / I

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12
Q

What can we say about current through a resistor to potential difference?

A

Current through a resistor is DIRECTLY PROPORTIONAL to the potential difference.(Resistor is an example of an OHMIC CONDUCTOR).

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13
Q

What key factor ensures that current through a resistor is directly proportional to the potential difference.

A

If the TEMPERATURE is constant.

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14
Q

How can resistors be useful in circuits?

A

Can be used to SHARE potential difference allowing for light for example to be DIMMER as less electrical energy is transferred to the lamp.

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15
Q

What can we say about current through a filament lamp to potential difference?

A

The current through a filament lamp is NOT directly proportional to potential difference. (Filament lamp is an example of a NON-OHMIC CONDUCTOR).

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16
Q

Why is the current through a filament lamp not directly proportional to the potential difference?

A

This is because the filament gets HOT so the RESISTANCE INCREASES.

17
Q

What is key about current in diodes?

A

The current flows in ONE DIRECTION only.

18
Q

What can we say about current through a diode to potential difference?

A
19
Q

Why can the current only flow through one direction in a diode?

A

As it has a very high resistance in the reverse direction.

20
Q

Why are diodes useful?

A

For controlling the flow of current in circuits.

21
Q

What can we say about resistors in series circuits?

A

The resistors ADD together.

22
Q

What can we say about resistors in parallel circuits?

A

The TOTAL RESISTANCE of two resistors is LESS than the resistance of the SMALLEST individual resistor.

23
Q

Label the live, neutral and earth wire on plug:

A
24
Q

What is the current in UK mains electricity?

A

Alternating current (AC). The current is constantly changing dicrection.

25
Q

What is the main benefit of using AC?

A

It is very easy to use a transformer to increase or decrease the potential difference.

26
Q

What is the frequency and potential difference of alternating current in the UK?

A

50Hz and 230v

27
Q

How can scientists see the pattern of an electrical current?

A

Using an oscilloscope

28
Q

What does a AC graph look like?

A
29
Q

What does DC graph look like?s

A
30
Q

How would you calculate the frequency of this wave?

A