T Level Technical Qualification in Design and Development for Engineering and Manufacturing (8714) > Unit 8 > Flashcards

Unit 8 Flashcards

Electrical and electronic principles (101 cards)

Study These Flashcards
1
Q

What are some examples of key symbols used commonly in electrical principles?

A

AC, DC, A, ω, Hz, emf, Wb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Give the names of these symbols in order: AC, DC, A, ω, Hz, emf, Wb

A

Alternating current, Direct current, Ampere, Angular frequency, Hertz, electromagnetic force, Weber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are some more examples of key symbols used commonly in electrical principles?

A

F, B, Z/R, Ω, φ, W, V, J

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give the names of these symbols in order: F, B, Z/R, Ω, φ, W, V, J

A

Farad, Flux density, Impedance/Resistance, Ohms, Magnetic flux, Watt, Volt, Joule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is magnetism?

A

A property of material where spinning electrons produce a magnet with a north-south pole to produce a magnetic field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In a magnetic field drawing, what are the lines surrounding the magnet called?

A

Magnetic flux lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the formula for flux density?

A

B = φ / A (B measured in teslas (T)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How can you produce an electromagnetic force?

A

By using a flowing current through a coil of wire

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the formula for magnetic field strength and what do the units mean?

A

H=I*N/L H=magnetic field strength, I=current, N=number of turns of coil wire, L=inductance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is electricity?

A

The movement of electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can free electrons do?

A

Easily attract other electrons from other atoms when they’re positively charged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between a conductor and an insulator, in terms of electrons?

A

A conductor has free electrons -> can conduct electricity, insulators have very little free electrons -> cannot conduct electricity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is Fleming’s left-hand rule?

A

A way to determine the direction of a force in a current carrying conductor in a magnetic field.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the right-hand grip rule?

A

Used to describe the magnetic field and direction of current in a metal core wrapped in wire.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are Faraday’s laws?

A
  1. Induced emf is established when magnetic field’s link to circuit, is changed
  2. Magnitude of emf is equivalent to rate of change in magnetic flux linking that circuit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is Fleming’s right-hand rule?

A

A way to measure the direction of current using the magnetic field and direction of force.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the difference between Fleming’s left-hand rule and right-hand rule?

A

Left hand rule = measures motors, Right hand rule = measures generators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do transformers do?

A

Used to change the levels of voltage (e.g. step up or step down transformers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

A potential of __ appears across a resistance of __ when a ________ __ __ _____ _______ ____ __________.

A

1V, 1Ω, current of 1A flows through that resistance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the voltage drop?

A

The reduction in voltage across a circuit when a current flows through it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is Ohm’s law?

A

Where voltage is proportional to the current flowing through a circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the formula for Ohm’s law?

A

V=I*R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

A circuit has a supply voltage of 50V, the current running through the circuit is measured at 15A, what is the resistance?

A

50=15*R -> 50/15=3.3 3.3Ω

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the formula for determining current using quantity (C) and time (s)?

A

I=Q/t

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are the various formulas to work out energy (J)?
W=I*R x I*t, W=I^2*R*t, W=V*Q
26
What is a Joule?
Measure of energy when 1C (coulomb) of electricity passes through a resistance of 1Ω
27
What is power?
Rate of work done, measured in Watts (W)
28
What is a multimeter?
A digital machine that measures voltage, current AND resistance at the same time.
29
What is the first step you need to do in a circuit before measuring resistance?
Switch the supply off to avoid error if other components are connected in parallel.
30
What is a capacitor?
A capacitor stores energy by using two plates that are separated by an insulator called a dielectric
31
What is the formula for measuring the quantity of change on the plates?
Q=C * V
32
What happens when a capacitor is used in direct current vs alternating current?
DC- Capacitor charges up its supply voltage but flow of current stops, AC - flow of current appears straight through capacitor with little to no resistance
33
What is capacitance measured in?
Farads (F)
34
Since farads are large units on their own, what standard units of capacitance is used instead?
Microfarad (μF) 1μF = 10-6 F, Nanofarad (nF) 1nF = 10-9F, Picofarad (pF) 1pF = 10-12F
35
How do you calculate the total capacitance in a circuit?
CT=C1+C2+C3 (parallel) 1/CT = 1/C1 + 1/C2 + 1/C3 (series)
36
What is an inductor?
Component that stores energy in a magnetic field using a coil of wire around a material.
37
What is the unit for inductance?
Henry (L)
38
How do you calculate energy in a **capacitor**?
E=1/2 * C*V^2
39
How do you calculate energy in an **inductor**?
W=1/2*L*I^2
40
A capacitor has 50C of charge and a 25V supply, what is its energy?
1/2*50*(25)^2 = 15,625J
41
In a direct current, the voltage is what?
Constant, resulting in current flow in one direction
42
In an alternating current, what happens to the **voltage**?
Changes from positive to negative over time, resulting in the current changing from positive to negative over the same period.
43
How do you work out voltage and resistance in a series circuit?
V=V1+V2+V3 or RT=R1+R2+R3
44
How do you work out voltage and resistance in a **series** circuit?
V=V1+V2+V3 and RT=R1+R2+R3
45
How do you work out current and resistance in a **parallel** circuit?
I=I1+I2+I3 and 1/RT+1/R1/R2+1/R3
46
What is Kirchhoff's law about current?
The sum of the currents entering = sum of currents leaving
47
What is Kirchhoff's law about voltage?
Around any closed loop, the sum of emfs in that loop (V) is equal to the sun of voltage drops in that loop (V1,V2,V3)
48
How do you solve a two loop circuit problem?
1. Choose direction of current, equate currents to satisfy Kirchhoff's laws 2. Consider each loop and use an equation which satisfies the laws 3. Pair of simultaneous equations which can be solved
49
A switch has closed in a circuit, what happens to the **current** if that circuit has a capacitor?
Current instantly increases to I=V/R, as capacitor charges up, current reduces drastically, after some time, current is zero
50
A switch has closed in a circuit, what happens to the **potential difference** if that circuit has a capacitor?
Potential difference across capacitor is initially zero because no resistance, as capacitor charges up, potential difference increases but decreases across the resistor.
51
What is the time constant of a circuit?
Time it takes for a circuit to fully charge, measured in Ꞇ (tau) seconds.
52
A switch is closed in a circuit, what happens to the **current** if that circuit has an **inductor**?
Current cannot rise instantly because of self-induced emf in inductor which opposes voltage, after some time, current will increase to a maximum limited only by resistance.
53
What are the two formulas for the time constant?
Ꞇ = C x R and Ꞇ = L/R
54
What does the magnitude of an emf depend on in a fixed magnetic coil?
The position of the field
55
The speed of rotation determines, what?
How quickly the voltage increases
56
What is the unit for frequency?
Hertz (Hz)
57
What's the formula for working out the time of one cycle?
Frequency = 1/T (time period)
58
What does it mean when the current is **in phase** with the voltage?
It operates at the same frequency.
59
What happens to the current in a purely inductive circuit?
Current lags the voltage
60
What happens to the current in a purely capacitive circuit?
Current leads the voltage
61
How do you work out the total phasor voltage?
By adding all the phasor additions' voltage together
62
What is the formula for **inductive reactance**?
XL = ωL= 2πfL Ω and VL = IXL
63
What is the formula for **capacitive reactance**?
XC = 1/ωC= 1/2πfC and VC = IXC
64
How do you calculate impedance (Z) in an RL/RC series circuit?
Z=√R^2 + XL^2 or XC^2
65
How do you calculate impedance (Z) in an **RLC** circuit for when current is either lagging or leading?
Z=√R^2+(XL-XC)^2 (lagging) or Z=√R^2 + (XC_XL^2) (leading)
66
How do you work out the true power?
P=I^2*R*W
67
What is a diode?
A semi conductor that allows flow of current in only one direction.
68
Why does an AC source have to be rectified to DC before connections to the battery can be made?
So that the energy is full wave meaning, it's a constant supply of energy.
69
What is one application of a diode?
Converting power coming from a power supply to power running from a battery.
70
What is a rectifier?
Circuits that are made up of one diode (half wave) or four diodes (full wave)
71
What does doping mean?
A process used to chemically change to control a diode's electrical properties.
72
What is the difference between an N-type and a P-type?
N-type = has extra electrons with a negative charge, P-type=effect of positive charge created from absence of electrons creating a positive hole
73
What happens in the depletion layer of a P-N junction?
Holes from P-side are repelled by +ve connection, electrons repelled by -ve connection, causes a reduction in depletion layer.
74
How does the depletion layer force current into one direction only?
Free charges are now attracted to the +ve and -ve connections, widening the layer, preventing current flow.
75
What is a transistor?
A three way P-N junction, such as NPN and PNP
76
What are the three connections called?
Base, collector and emitter
77
What is the difference between an NPN and PNP transistor?
NPN = Base->Emitter PNP = Emitter->Base
78
How do transistors work?
They apply a small voltage to the base, current will flow between collector and emitter
79
How does a transistor act as an amplifier?
Current flow is larger between collector and emitter junction then current supplied to base.
80
The current flowing between collector and emitter is larger than the base current. This is __ _______ ____ __ __ _________.
the current gain of an amplifier.
81
Give one common application of a transistor.
Used to amplify small currents in musical applications, Used to regulate current to propulsion drives on big cruise ships
82
Why does internal heat need to be removed when using a transistor for high power applications?
Power loss would be in kW which would destroy the device entirely.
83
How do you remove the **internal heat** in a transistor?
Forced air cooling or water cooling
84
Why does water purity have to be very high for water cooling?
Because of its increased electrical resistance.
85
How is **water** conductivity measured in?
Microsiemens (μS)
86
Give three reasons why protection systems are essential in electrical applications?
To prevent electric shock To isolate faulty circuits To provide good isolation for maintenance To prevent damage to equipment
87
What should protection equipment be capable of isolating?
Prospective fault current
88
Why are voltage and current transformers used for protection systems?
They are used to measure large voltage and current in high power systems, reducing them to more manageable levels
89
What is a residual current device used for?
Measuring difference in current between two conductors: a live conductor and a neutral conductor
90
A person accidentally touches the live conductor of the RCD, what does the RCD do to keep you safe?
If there is a small difference between supply and return current, the device will trip the circuit.
91
What is used to protect electrical equipment from lightning?
Lightning arrestors
92
What does a lightning arrestor do?
Allows current surge to flow to the earth when a spark crosses the air gap.
93
What is an analogue signal?
Type of continuous time-varying signal
94
How can an analogue signal be defined and what does it represent?
Amplitude, time period or frequency, process variables like temperature, pressure or flow
95
Give one limitation of analogue signals
They can become distorted which means information they carry can be corrupted
96
What is a digital signal?
Data as a sequence of values, usually a binary or logic signal
97
How does signal conditioning work?
Converts signals into the same type of analogue signal which represents individual values (ex. pressure to current converter)
98
How does an analogue to digital converter work?
Converts analogue signals to **binary representations** of the varied analogue value.
99
How does signal processing work?
Takes digital information and feeds it digitally or through an analogue format, using a digital to analogue (D/A) converter
100
100
What is a logic gate?
A series of transistors connected together to give one or more outputs based on one input or a combination of inputs.
T Level Technical Qualification in Design and Development for Engineering and Manufacturing (8714)
flashcards
Decks in class (17)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions