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p2 Flashcards

(95 cards)

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1
Q

what happens if you close an open switch

A

electrons flow out of the cell and move around the circuit to the negate end to positive

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2
Q

what do u call a flow of electrons

A

an electric current

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3
Q

what is a series circuit

A

when it has no branches

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4
Q

what is a current

A

a flow of electrical charge around the circuit

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5
Q

what is the unit of current

A

ampere amps A

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6
Q

how do we measure a current

A

with a ammeter

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7
Q

what is the same in a series circuit

A

the current is the same all the way around

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8
Q

what do u call it when scientist draw the current in th e opposite direction

A

the conventional current

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9
Q

what dose a parallel circuit contain

A

branches

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10
Q

what dose the branches mean in a Parallel Circuit

A

that the current splits

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11
Q

Work out the current leaving the cell in a parallel circuit

A

0.7 amps

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12
Q

What are circuits like this called

A

Series circuit because it has no branches

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13
Q

What dose the current in the branches add up to in a Parallel circuit

A

Adds up the total current leaving the cell

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14
Q

What is the energy transfer in this circuit

A

The cell stores a chemical energy the. Is transferred to the electrical energy which is carried by the electrons passing out the cell when it passes through the lamp it’s transferred to a different energy in the lamp it’s light energy and thermal energy

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15
Q

What is the energy transfer in this circuit

A

The cell stores a chemical energy the. Is transferred to the electrical energy which is carried by the electrons passing out the cell when it passes through the lamp it’s transferred to a different energy in the lamp it’s light energy and thermal energy

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16
Q

What is potential difference also known as

A

Voltage

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17
Q

What does the potential difference of 1 volt tells us vine

A

That there’s 1. Joule of energy is transferred for each coulomb of charge that is moving through the circuit

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18
Q

What is pd measured with

A

A volt meter

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19
Q

Are the lights dimmer or lighter in this circuit

A

Dimmer

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20
Q

Describe the energy current between this two lamps

A

The total energy carried by the current has been shared between the two lamps

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21
Q

What has to add up in this circuit

A

The two lamps is the same as the p.d across the cell

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22
Q

Describe what’s happening in this cell

A

The cell has a pd of 9 volts which means that 9 joules of energy is transferred fir every coulomb of charge then is shared between the two lamps the p.d of 6 volts will be more

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23
Q

Is the pd in parallel circuits the same

A

Yes the volt between each component is the same

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24
Q

What is the pd across the bottom lamp in the parallel circuit

A

Pd is 2 volts

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25
A cell has a pd if 9 volts what will it be if we add a battery
You will do 2 x 9 = 18 18 volts
26
A cell has a pd if 9 volts what will it be if we add a battery
You will do 2 x 9 = 18 18 volts
27
1 cell is = to 9 volts work out the pd of the battery
Volt of the battery = 0 It cancels out
28
What is the pd of the battery 1 cell = 9 volts
It will be 9x 2 = 18 but one cell is facing the wrong direction which will cancel out one of the cells = only 9 volts
29
What is electrical charge measured in
Coulombs (C)
30
What does a current of 1 ampere =
1 coulomb of change flowing per second
31
The size of electrical current is the
Rate flow of electrical charge
32
What equation do we use to work out the charge flow in a circuit
H
33
What equation do we use to work out the charge flow in a circuit
H
34
0,3 x 20 =6c
35
36
What is the calculation of energy transfer
37
38
25 + 5 = 30 5 x 3 = 15 joules
39
What does the resistance tells us
How much energy is required to push coulomb of charge through
40
What’s the difference between lamp A and lamp B
I’m lamp a it has a low resistance but lamp b has a high resistance
41
What’s the equation for resistance
42
What is the resistance of the lamp
10 divided by 1 The pd divided by the current = 10
43
What is the equation to work out the pd needed to produce a certain current
44
45
What happens to the electrons when they move through a conductor
They collide with atoms in the metal
46
The higher the resistance
The more energy is transferred as the current moves
47
Is a lot of energy wasted in resistance
Yes
48
What do we use when we want to add resistance into a circuit
To do that we use a resistor
49
What do we do if we wanted to make the lamp dimmer
We could add a resistor the pd is shared between the lamp and resistor less electrical energy going to the lamp
50
What does the A mean
Current
51
What does the v mean
Potential difference
52
C & v
Currrent volts
53
Does the resistance change if we increase the current
No the resistance is constant
54
What is it called when a resistor is constant
An ohmic conductor
55
The resistance will only stay constant if the ……
Temperature is constant
56
What does filament mean
A very thin wire
57
During electrical current passes through the filament lamp the wire gets
extremely hot causing it to give out light
58
What type of graph do we get from changing the pd of the filament lamp and measuring the current in a circuit
It’s not directly proportional to the pd
59
What type of graph do we get from changing the pd of the filament lamp and measuring the current in a circuit
It’s not directly proportional to the pd
60
Why was the filament lamp directly proportional
Because the filament gets hot causing the resistance to increase
61
At high temperatures the atoms and the filament
Vibrate more that means the electrons and current now collide more with the atoms more energy is push the current through the filament
62
Describe what’s happening in the graph
As the pd increases the current no longer increases as much which feels us that resistance is increasing
63
Is a filament lamp a ohmic conductor
No it’s not it’s not constant
64
What way dose the current flow through a diode
At one direction only due to the diode having a very high resistance in the reverse direction
65
Explain what’s happening to the diode here
The cell is turned and the cell is now flowing in the opposite direction that’s means the diode will now all the current to pass through due to the diode high resistance in the reverse direction
66
For the graph diode can current flow on the opposite direction
No it’s can’t
67
The graph for diode
68
What are diodes useful for
For controlling the flow of current in circuits
69
Where are leds found in
Tv ligh flash light bulb
70
Where are leds found in
Tv ligh flash light bulb
71
What does led stand for
Light emitting diode
72
An led only flow In
One direction as like the diode
73
What dose an led gives off
It gives off light when a current flows through
74
What do resistors in series do
Add together
75
What dose LDR mean
Light depending resistor
76
In the light the resistance of the LDR
Is very low
77
The graph for LDR
Low light intensity high resistance High light intensity low resistance
78
The graph for LDR
Low light intensity high resistance High light intensity low resistance
79
The graph for LDR
Low light intensity high resistance High light intensity low resistance
80
What’s happening hereb
In the light when the phone is not held to tor ear is resistance of the LDR is very low which mean it takes very little energy to pass through the LDR because of The pd across the ldr is very low ( takes very little energy to pass through for the current to pass through the LDR )
81
The pd is shared between components in
Series so that means the pd across the lamp is large the lamp now lights up the scream
82
What happens if the phone is held to your ear
The LDR is in darkness the resistance of the LDR rises sharply now. It takes a great deal of energy for the current to pass through the LDR so the pd across the LDR is very high which mean less electrical energy is available for the lamp the pd across the lamp is low the lamp becomes very dim Thai turns the scream off
83
The resistance of the thermistor decreases if the temperature
Increases
84
The resistance of the thermistor decreases if the temperature
Increases
85
What’s happening here
Under cool condition the thermistor is high it takes a lot of energy for the current to pass through the thermistor the pd across the thermistor is high the pd across the fan is small
86
What’s happening here
If the computer gets hot the resistance of the thermistor falls now It takes much less energy fir the current to pass through the thermistor this mean the pd across the thermistor is low so. more electrical energy is is available for the fan which makes the pd across the fan very high so the fan powers to high speed and cools the computer down
87
How do we increase the length of the wire practical 3 resistance
We attach the wire to a meter ruler using tape now we connect the wire to the rest of the circuit using 2 crocodile clips only the one with the two crocodile clips is connected to the circuit we can move it further away now we can change the. Length of the wire and measure the resistance in the circuit
88
What is the graph for required practical 3
The wire is Directly proportional to the length
89
What are the issues about practical 3
If we look at the graph there’s a small resistance when the length of the wire is zero and that should not be there which is not an actual result called a zero error
90
What is a zero error
Is a reading on a measuring instrument when the value should be zero It’s a systematic error we cannot reduce it by carrying out repeats In the case of resistance we need to subtract the zero error form all our readings
91
What is the zero caused by in the practical 3 resistance
It’s caused by the requirement it’s extremely difficult to get the crocodile clip at the zero position on the ruler There also come resistant caused by the contact between the crocodile clip and the wire ( nothing we can do )
92
What is the other affect in the practical 3 resistance other than the zero effect
Is the heating effect If the temperature of the wire increases than the resistance will also increase
93
What can we do to stop the heating effect
We can use a low pd this will keep the current low reducing any heating in the wire We should only turn on the current when were taking a reading Turn off current between readings
94
How do we increase the resistance in a circuit
By using a longer wire
95
What does a variable resistor contain
A long piece of wire and a coil

physics (24 decks)

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