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PHYSICS > CHAPTER 4 > Flashcards

CHAPTER 4 Flashcards

(60 cards)

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1
Q

Do you use ammeters in series or in parallel

A

series

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2
Q

In a parallel circuit, how do you calculate the total current

A

The total current is the sum of the currents in the separate sections

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3
Q

In a parallel circuit what is important to remember about the potential difference across each component

A

it is the same

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4
Q

In a parallel circuit the bigger the resistance…

A

The smaller the current

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5
Q

How to calculate current using potential difference and resistance

A

Current = potential difference/resistance

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6
Q

When you add more resistors in a parallel circuit why does the total resistance decrease

A

The total potential difference is the same so the total current increases. The total resistance = pd/current, so this means the resistance is less

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7
Q

In a series circuit, what is important to remember about the current

A

The current passing through each component is the same

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8
Q

How do you calculate the total potential difference of a series circuit

A

Add up the potential differences of all components

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9
Q

How to find the total resistance in a series circuit

A

Add up the resistance of each component

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10
Q

When you add more resistors in a series circuit, why does the overall resistance increase

A

The total potential difference is shared across more resistors, giving each one less. This means that the current decreases, and as the total pd doesn’t change, this means that the total resistance is greater than before

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11
Q

How to calculate resistance using pd and current

A

Resistance = pd/current

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12
Q

What is a diode

A

A non ohmic conductor

Only lets current flow in one direction

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13
Q

What is a light emitting diode

A

Emits light when current flows through it in a forward direction

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14
Q

What is a thermistor

A

Temperature dependent resistor

Resistance decreases when temperature increases

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15
Q

Why are ammeters connected in series

A

So the current across them and the component is the same

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16
Q

Is a voltmeter wired in parallel or series

A

Parallel

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17
Q

Why is a voltmeter connected in parallel

A

So it measures the pd across it

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18
Q

What is resistance

A

Resistance is when the electrons travelling around the circuit have to push through the ions in the metal filament

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19
Q

How to calculate resistance using pd and current

A

Resistance = pd / current

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20
Q

What is the current through a resistor directly proportional to

A

The potential difference across the resistor

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21
Q

What is Ohm’s law

A

The current through a resistor at constant temperature is directly proportional to the pd

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22
Q

Function of the cell

A

Pushes electrons around a complete circuit

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23
Q

Function of switch

A

Enables current to be turned on and off

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24
Q

Function of bulb

A

To indicate when a current is passing through the circuit

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25
What is an ammeter
Used to measure electric current
26
Function of fixed resistor
Limits current in circuit
27
Function of variable resistor
Allows current to be varied
28
Function of fuse
Melts to break circuit when current is too high
29
Function of heater
Used to transfer energy from an electric current to heat surroundings
30
Function of voltmeter
Measures voltage/pd
31
How to calculate charge flow using current and time
charge flow = current x time
32
What is the name for a charged atom
An ion
33
What happens when an object becomes charged
It loses or gains electrons
34
What type of forces attract
opposites
35
What is a charged atom called
An ion
36
How do objects become hatched by friction
Electrons are transferred
37
Where is an electric field strongest
Nearest to it
38
What direction do electric field line go in
Positive to negative
39
What happens to cause a spark
When there is a high PD between an object and an earthed object High PD = strong electric field This pulls electrons out of the air molecules This makes air conductive so a current can flow through causing a spark
40
What does the voltage of a battery tell you
How much energy it transfers to each coulomb of charge
41
What is the direction of current
Positive to negative
42
Why is a wire an ohmic conductor
Its resistance stays constant
43
Why does increased temperature increase resistance
The atoms are vibrating more so they resist the passage of the electrons
44
Why is a diode a non ohmic conductor
The current isn't directly proportional to the PD
45
What happens to the resistance of an LDR if the light intensity increases
it decreases
46
Where does the current go in a series circuit
Through each component
47
What happens to the PD in a series circuit
It is shared between the components
48
What is the total PD of cells in a series circuit
The sum of all PDs
49
How to calculate resistance in series
Add the sums of all the resistances together
50
Why does adding more resistance in series increase the total resistance
The current through the resistors is less and the PD is unchanged
51
How to find the total current in a parallel circuit
The sum of the currents through the separate branches
52
What is the pd of components in parallel
the same
53
How to work out the total resistance in parallel
R1 + R2 _____ R1 + R2
54
Potential difference of live wire
230V
55
Potential difference of people
0V
56
Why do you get an electric shock when you touch a live wire
wire = 230 v people = 0 v large potential difference between us and wire so charge passes through us
57
What is current
A flow of electrical charge
58
What is the potential difference
The pushing force which drives the charge around the circuit
59
Why do you get an electric shock when you touch live wire
people = 0v | large potential difference between us and wire so charge passes through us
60
How does rubbing a rod with a cloth cause it to become charged
There is friction between the two | This causes electrons to move from the objects which leaves the charge on one positive and the other negative

PHYSICS (16 decks)

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