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Additional Science > P2.4 > Flashcards

P2.4 Flashcards

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1
Q

Why does a TV screen crackle when switching it on?

A

Charged with static electricity so it becomes electrically charged.

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2
Q

What subatomic particles are in the nucleus of an atom?

A

Protons and neutrons.

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3
Q

Where are the electrons in an atom?

A

Moving about in the space around the nucleus.

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4
Q

What is the charge of each subatomic particle?

A

Protons-positive
Neutrons-no charge
Electrons-negative

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5
Q

What is an uncharged atom?

A

Atom that has equal number of protons and electrons.

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6
Q

What is a charged atom called?

A

An ion.

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7
Q

How do some insulators become charged?

A

By rubbing them with a dry cloth.

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8
Q

What happens when you rub a polythene rod with a dry cloth?

A

It transfers electrons to the surface.

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9
Q

What happens when placing two objects with the same type of charge next to each other?

A

They repeal each other.

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10
Q

What happens when you place two objects that have different types of charge next to each other?

A

They attract each other.

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11
Q

What does a circuit diagram show?

A

Shows us how the components in a circuit are connected together.

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12
Q

What is an electric current?

A

Flow of charge.

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13
Q

What happens when an electric torch is on?

A

Electrons pass through the torch bulb and through the cell every second.

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14
Q

What do the electrons do to the positive ions in a metal?

A

Stops he ions from moving away from each other.

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15
Q

Why do the electrons pass through the bulb?

A

Because its filament is made of a metal.

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16
Q

What do the electrons transfer and to where?

A

Transfer energy from the cell to the torch bulb.

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17
Q

What is the size of an electric current?

A

The rate of flow of electric charge.

Per second

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18
Q

What happens if you increase the number of electrons passing through a component?

A

The current passing through it becomes bigger.

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19
Q

What is the electric charge measures include?

A

Coulombs (C)

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20
Q

What is an electric current measured in?

A

Amperes (A) or amps

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21
Q

What is the rate of flow of charge if the electric current is 1 amps?

A

It’s also 1 coulomb.

22
Q

What is the equation for the current in amps?

A

=charge flow in coulombs/time taken in seconds

23
Q

What is the equation for the potential difference across the component in volts?

A

=work done in joules/charge in coulombs

24
Q

What is he equation for resistance?

A

=potential difference(volts)/current(amps)

25
Q

What do the electrons have to do?

A

Push their way through lots of vibrating ions in the metal filament then the ions resist the passage of electrons through the torch bulb.

26
Q

What is he unit of resistance?

A

Ohm

27
Q

What does the resistor limit?

A

The current.

28
Q

What is the current throughout resistor at constant temp directly proportional to?

A

To the potential difference across the resistor.

29
Q

Why do we say a wire is ohmic conductor?

A

Because its resistance is constant.

30
Q

Why doesn’t reversing the pd make a difference to the shape of the line?

A

Because the resistance is the same whichever direction current is in.

31
Q

What does a straight line through the origin mean?

A

That the current is directly proportional to the potential difference.
The resistance is constant.

32
Q

If the line curves away from the axis what does it say about the current?

A

Not directly proportional to the potential difference.

33
Q

What happens to the resistance if the current increases?

A

It increases.

34
Q

Why does the resistance increase as the the temperature increases?

A

Because the ions in the metal filament vibrate more as the temperature increases.

35
Q

In the forward direction, how is the line in a diode graph? What happens to the current?

A

Line curves towards the axis.

Current is t directly proportional to the potential difference.

36
Q

In the reverse direction, what is he current in a diode graph? What happens to the resistance?

A

Current is negligible.

Resistance in the reverse direction is much higher that in the forward direction.

37
Q

What does a thermistor show?

A

Shows the current-potential difference graph at two different temperatures.

38
Q

What does a light-dependent resistor show?

A

Shows the current-potential difference graph in bright light and in dim light.

39
Q

Why does the same current pass through components in series with each other?

A

Because the same number of electrons are passing through each component every second.

40
Q

What is the potential difference of a cell?

A

It’s a measure of the energy transferred from the cell by each electron that passes through it.

41
Q

When is the rule, the potential difference of the cell is shared between the bulbs, applied?

A

When each electron in the circuit goes through both bulbs.

42
Q

What happens to the potential difference when the cells act in the same direction?

A

The total potential difference of cells in series is the sum of the potential difference of each cell.

43
Q

What happens when we use two or more cells in series in a circuit?

A

Each electron gets a push from each cell provided that each cell is connected so they act in the same direction.

44
Q

What does the share of the cell’s potential difference across each component depend on?

A

Depends on the setting of the variable resistor.

45
Q

What is the equation for the resistance?

A

= R1 + R2

46
Q

What is the total resistance of components equal to?

A

Equal to the sum of the resistance of each component.

47
Q

What is a bypass?

A

A parallel route.

48
Q

What rule is applied when components are in parallel?

A

The current through the cell is equal to the sum of the currents through the two bulbs.

49
Q

What is the potential difference for components in parallel?

A

Potential difference across each component is the same.

50
Q

What is the equation for the current?

A

=potential difference(volts)/resistance(ohms)

51
Q

What happens to the current if the resistance becomes bigger?

A

The current through it becomes smaller.

52
Q

Which resistor passes the smallest current?

A

The ones that have the largest resistance.

Additional Science (18 decks)

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