GCSE-CurrentElectricity Flashcards

1
Q

Total current entering or leaving the battery in a parallel circuit equals the …?… …?… the currents in the branches

A

sum of

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2
Q

The voltage across each branch in a parallel circuit is …??…

A

the same

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3
Q

Equation for total Resistance of a series combination of resistors

A

Rtotal = R₁ + R₂ + R₃…

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4
Q

electrical power equation

A

P = VI

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5
Q

Electric energy equation

A

E = ItV

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6
Q

Equation for total Resistance of a parallel combination of resistors

A

1/Rtotal = 1/R₁ + 1/R₂ + 1/R₃

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7
Q

Alternative equation for total resistance of a parallel combination of 2 resistors only.

A

Rtotal = product/sum

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8
Q

Equation for Ohm’s Law

A

V = IR

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9
Q

Equation to find energy used in kilowatt-hours (kWh)

A

kWh = power in kW x time in hours

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10
Q

The size and direction of direct current (d.c) are both …?

A

constant

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11
Q

The size and direction of alternating current (a.c) both continually…?

A

change.

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12
Q

The unit for power

A

Watt (W)

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13
Q

Equation for total voltage across cells in series

A

V = V₁+V₂+V₃ + …

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14
Q

Equation for the total voltage across components in a series circuit

A

V = V₁ + V₂+ V₃ + …

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15
Q

The current at every point in a series circuit is …?

A

the same.

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16
Q

The equation that links electric current and charge

A

Q = It

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17
Q

The voltage across each branch in a parallel circuit equals the…?

A

supply voltage

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18
Q

As the current through a filament lamp increases the resistance of the filament …?

A

increases

19
Q

A component which allows electric current to flow through itself only in one direction is called a …?

A

Diode

20
Q

The unit of electrical resistance is the …?

A

Ohm (Ω)

21
Q

The unit of electrical current is the …?

A

Ampere (A)

22
Q

The unit of electrical potential difference is the …?

A

Volt (V)

23
Q

The yellow and green wire in a three-pin plug is the …?… wire

A

Earth

24
Q

A good electrical conductor is a good electrical conductor because it possesses …??

A

free electrons

25
Q

A graph of V against I for a piece of metal wire at constant temperature is a …?????

A

straight line through the origin

26
Q

A graph of V against I for a light-bulb filament curves from …?… to steep.

A

shallow.

27
Q

Electrical current passing through a metal heats it up because of collisions between free electrons and the …?… in the metal

A

ions

28
Q

The total resistance R of two identical resistors r connected in parallel is …?

A

r/2

29
Q

If the length of a piece of wire is increased its resistance…?

A

increases

30
Q

If the diameter of a piece of wire is increased its resistance…?

A

decreases

31
Q

The Earth wire and …?… together protect the user from electric shock and the equipment from damage.

A

fuse

32
Q

General definition of power

A

P = E/t

33
Q

What colour is the live wire in a plug?

A

Brown

34
Q

What colour is the neutral wire in a plug?

A

Blue

35
Q

To which pin in a plug should the Earth wire be connected?

A

The top pin

36
Q

In a plug, which wire must be connected to the pin that has a fuse attached?

A

The live wire (brown).

37
Q

What is the function of the live wire in a circuit?

A

It carries current to the device.

38
Q

What is the function of the neutral wire in a circuit?

A

It carries current from the device.

39
Q

On what side of any device must any switch and any fuse be connected?

A

The live side.

40
Q

Equation linking resistance and length for a metallic wire at constant temperature.

A

R=kL where k is a constant.

41
Q

How to find the total resistance of a combination including parallel and series sections.

A
  1. Find the resistance of each parallel section.
  2. Add these resistance values to those of the resistors in series.
42
Q

The gradient of a V against I graph at any point gives the …?… of the component at that current value.

A

resistance.

43
Q

Ohm’s Law in words.

A

For any metallic conductor at constant temperature, the applied voltage is directly proportional to the current flowing through the conductor.

44
Q

How to calculate the correct rating for a fuse.

A
  1. Calculate the normal current for the device using P=VI
  2. Choose the smallest fuse rating higher than the normal current.