Electricity Flashcards
1
Q
State what is meant by AC.
A
A current whose instantaneous value and direction varies with time.
2
Q
Which circuit component is represented by the following diagram?
A
Variable Resistor
3
Q
What happens if a positive and a negative charge are brought together?
A
They attract each other
4
Q
What is the energy change in a lamp?
A
Electrical to light (+ heat)
5
Q
Name one source of AC
A
Mains supply
6
Q
What is the rule for current in a series circuit?
A
The current is the same everywhere
7
Q
What happens if two positive charges are brought together?
A
They repel each other
8
Q
What is the energy change in a buzzer?
A
Electrical to sound
9
Q
Which circuit component is represented by the following diagram?
A
Capacitor
10
Q
What is a Light Dependent Resistor?
A
A resistor whose resistance changes with changes in light level
11
Q
What is the charge on a proton?
A
Positive
12
Q
What is current?
A
The charge transferred per second
13
Q
What would happen to an electron being fired through the electric field below?
A
It would experience a force and be attracted to the positive plate.
14
Q
How does a relay work?
A
- Close a switch to make a current flow in a wire.
- This creates an electromagnet.
- Electromagnet attracts metal switch.
- This completes the second circuit and the lamp switches on.
15
Q
What is the energy change in an LED?
A
Electrical to light
16
Q
Which device measures voltage?
A
Voltmeter
17
Q
Which particles are in the nucleus of the atom?
A
Protons and Neutrons
18
Q
What will be the voltage across a capacitor when it is fully discharged?
A
Zero volts.
19
Q
What happens if you increase the resistance in a circuit?
A
The current will decrease
20
Q
Which circuit component is represented by the following diagram?
A
Loudspeaker
21
Q
What is DC?
A
Direct current. Electrons move in one direction only.
22
Q
Which component does the symbol represent?
A
Buzzer
23
Q
Which circuit component is represented by the following diagram?
A
Thermistor
24
Q
What would the field lines around a positive point charge look like?
A
Field lines show direction away from the positive point charge.
25
How can you identify a series circuit?
It is a circuit with only one path round it.
26
Name one source of DC
Battery
27
How should a diode or LED be connected with a battery to light correctly?
Small line on battery points to small line on LED or diode.
28
Explain how a fuse works.
A fuse is a thin wire. If too much current passes through it, it will get hot and melt. This breaks the circuit.
29
Which device measures resistance?
Ohmmeter
30
What is electric charge?
An electric charge occurs when there are fewer or more electrons than protons.
31
Which circuit component is represented by the following diagram?
Light Emitting Diode
32
Which circuit component is represented by the following diagram?
Light Dependent Resistor
33
If you heat a conductor, what happens to it's resistance?
It increases
34
What is the rule for volatges in a parallel circuit?
The voltage across each branch is equal to the supply voltage.
35
Which circuit component is represented by the following diagram?
Battery
36
What does an electric field line show?
The direction a positive charge would move in that field.
37
Which circuit component is represented by the following diagram?
Lamp
38
What is AC?
Alternating current. The electrons change direction, moving backwards and forwards, many times in a second.
39
What is the function of a transistor?
Electronic switch
40
What two factors effect the running cost of an appliance?
The time it is used for The power rating of the appliance
41
How can a parallel circuit be identified?
It is a circuit with more than one path round it.
42
State a device that can be used in a light sensor
LDR
43
Which circuit component is represented by the following diagram?
Photovoltaic cell / solar cell
44
What is the symbol for a voltmeter?
Circle with a V in it
45
What is the energy change in a microphone?
Sound to electrical
46
What is the rule for selecting a fuse from a power rating?
Appliances less than 720W use a 3A fuse Appliances more than 720W use a 13A fuse
47
How can power losses be reduced in transmission lines?
By increasing the transmission voltage and so decreasing teh transmission current. Power loss P = I2R, so if the current is reduced the power lost is reduced.
48
What would the field lines look between parallel plates?
Field lines run from positive to negative plate, with a bulge at the ends of the parallel plate.
49
What is power?
The energy used per second
50
Which circuit component is represented by the following diagram?
Motor
51
Which circuit component is represented by the following diagram?
Fuse
52
What is the charge on a neutron?
No charge
53
Which device measures current?
Ammeter
54
What is the function of a MOSFET?
Electronic switch
55
Which circuit component is represented by the following diagram?
Transistor
56
For the diagram of the atom name the parts.
57
Which circuit component is represented by the following diagram?
Microphone
58
How can you tell from this oscilloscope image that this is AC?
The trace shows a change in direction
59
How should an ammeter be connected to measure the current in a component?
It should be connected in series with the component
60
How can you indicate a stronger electric field?
More field lines
61
What happens if you unscrew one of the lamps in the circuit below? Why?
The other lamps go out. There is a break in the circuit and the current does not have a complete route to the battery.
62
What is the energy change in a motor?
Electrical to kinetic
63
What is the rule for voltages in a series circuit?
The voltage across each component added together is equal to the supply voltage.
64
What is the effect of an electric field on a charge?
The charge will experience a force.
65
How is a uniform electric field represented?
Evenly spaced field lines
66
What is the energy change in a buzzer?
Electrical to sound
67
Which circuit component is represented by the following diagram?
Resistor
68
What is the charge on an electron?
Negative
69
What type of current is represented by this oscilloscope image?
DC
70
Which circuit component is represented by the following diagram?
Switch
71
What happens if two negative charges are brought together?
They repel each other
72
State two place a variable resistor can be used.
Light dimmer switch sped control on Scalextric cars volume control on a radio
73
What is meant by capacitance?
Charge stored per unit volt
74
What type of current is represented by this oscilloscope image?
AC
75
What is the symbol for an Ohmmeter?
Circle with an Omega in it
76
What would the field lines around a negative point charge look like?
Field lines show direction towards the negative point charge
77
Explain how electrostatics can be used in paint spraying a car.
Car is connected to a negative terminal so that it is negatively charged.
Spray gun is made positively charged so the paint particles are positive.
The poistive paint is attracted to the negative car.
Areas of the car already covered in paint will repel any more charged paint.
78
Which circuit component is represented by the following diagram?
Cell
79
Which circuit component is represented by the following diagram?
MOSFET
80
When would you use a relay?
To switch on a high current ciruit using a low current circuit for safety.
81
What is meant by the potential difference (voltage) of a supply?
It is the number of Joules of energy given to each coulomb of charge passing through the cell
82
What will be the voltage across a capacitor when it is fully charged?
The supply voltage.
83
Why is an LED normally connected in series with a resistor?
Resistor is to protect the LED by limiting the current in the LED.
84
What is the symbol for an ammeter?
Circle with an A in it.
85
What is the energy change in a photovoltaic cell?
Light to electrical
86
What is the rule for current in a parallel circuit?
The supply current is equal to the current in each branch added together.
87
What is a thermistor?
A resistor whose resistance changes with changes in temperature
88
Name one place that electrostatics can be used.
* Laser printers
* Paints spraying
* Cling film
* Forensic science
* Dust removal
* Electrostatic precipitators
* Electrostatic separators
89
What is the energy chage in a battery?
Chemical to electrical
90
Which circuit component is represented by the following diagram?
Diode
91
How can you indicate a weaker electric field?
Less field lines
92
What is the energy change in a loudspeaker?
Electrical to sound
93
What is a fuse?
Safety device that protects the flex
94
What is the stated value of the mains?
230V, 50Hz
95
What does a capacitor do?
Stores charge or energy
96
State a device that can be used in a temperature sensor
Thermistor
97
How should a voltmeter be connected to measure the voltage across a component?
It should be connected across the component
