Engineering materials

Students Learn About:

- specialised testing

– voltage, current, insulation

– signal strength and testing

- copper and its alloys used in telecommunications including copper beryllium, copper zinc, electrolytic tough pitched copper

– structure/property relationships and their application

semiconductors such as transistors, zener diodes, light emitting diodes and laser diodes

– uses in telecommunications

polymers

– insulation materials

- fibre optics

– types and applications

– materials

Students Learn To:

analyse structure, properties, uses and appropriateness of materials in telecommunications engineering applications
select and justify materials and processes used in telecommunications engineering
identify the types and functions of common semiconductors used in the telecommunications industry
describe the uses and applications of polymers and fibre optics in telecommunications

HSC Quick Notes 📝

- specialised testing

• Voltage is like the water pressure. It’s how hard the water is being pushed through the hose. More pressure means the water wants to move faster.

• Current is like the flow of water. It’s how much water is actually moving through the hose every second.

• Resistance is like squeezing the hose or having a knot in it. It makes it harder for the water to flow.

So:

• High voltage = strong push.

• High current = lots of flow.

• High resistance = harder for it to flow.

voltage

current

resistance

Voltage is often described as "electrical pressure' - a voltage is caused by one point having more or less electrons than another point along a conductor. Voltage is measured in Volts, - V or E for Electromotive Force (EMF).

Electricity tries to reach equilibrium so the electric charge 'flows' from the high pressure (more electrons) area to the low pressure (less electrons) area. When both areas have the same number of electrons (equilibrium) no further movement of electrons occurs and the flow of current ceases.

A potential difference or voltage difference is always measured between or across two points in a circuit.

Current is the measure of charge movement in a conductor - measured in Amperes or Amps (A).
Free electrons are the charge carriers in electrical conductors.
With no external force applied (ie no voltage), the net flow of electrons in a conductor in any one direction is zero.
For current to flow there must be a complete circuit.
The current flowing in one end of a conductor must flow out of the other end ie. the electrons must be consumed at the positive end.

The flow of charge through any material encounters an opposing energy loss due to collisions between electrons as well as with other atoms in the material. this is electrical resistance (R) and it is measured in ohms (S). These collisions convert electrical energy into heat because the process constitutes a resistance to charge flow, and necessitates the application of voltage to maintain current

In general with temperature increase, resistance increases in metals but decreases in semiconductors. Also larger cross-sectional areas of conductors reduce resistance. Cold working and alloying generally increases resistance.

Silver is the best conductor as it has the lowest resistivity. Copper, gold and aluminium are also good conductors while some metals, like titanium, have a relatively high resistivity. Gold is used for high-quality surface-to-surface contacts because it does not oxidise. Ceramics, plastics, wood and air have a high resistivity and are thus classified as insulators.

insulation

Conductors are those materials that permit a generous flow of electrons with very little voltage applied. Metals are good conductors because they have more free electrons than other materials mainly because of the metallic bond.

Insulators are those materials that have very few free electrons because they usually are covalently and/or ionically bonded and thus require a very large voltage to establish a measurable current.

Semiconductors are a specific group of elements that exhibit characteristics between those of insulators and conductors.

• Voltage, current and resistance in AC and DC circuits can be tested using various instruments such as a multimeter or cathode ray oscilloscope (CRO). Resistivity of a material will determine it's suitability as an insulator or resistor (high resistance) or as a suitable conductor (low resistance).

• A standard tool for insulation testing is a Megohmmeter ('Megger' test) which measures resistance values of the insulation when a 500 to 5,000 volt DC current is passed through the insulated conductor.

• Signal strength refers to the magnitude of the electric field at a reference point from the transmitting antenna, usually expressed as voltage per metre. In analog and digital communications, signal-to-noise ratio, (SNR) is a measure of signal strength relative to background noise. The ratio is usually measured in decibels (dB).

signal strength and testing

Concept Check

Wifi treasure hunt! Use the google speed test to find the fastest download and upload speeds in the school over wifi.
What factors do you think contribute to the speeds in the area you have choosen to speed test in.

- copper and its alloys used in telecommunications

Explain Signals In Copper

A signal in copper is an electrical pulse that travels through a copper wire or cable to transmit data. Copper's high conductivity allows it to carry signals, but its physical properties cause signal degradation, or attenuation, and electromagnetic interference (EMI) over distance and at high frequencies. This limits the effective range of copper cables to typically 100 meters for high-speed data, requiring repeaters for longer distances.

Compare Copper and Fibre

Short

Limitations of Copper Cables

Signal Attenuation:

Over distance, the strength of the electrical signal weakens, a process known as attenuation.

Electromagnetic Interference (EMI):

The magnetic fields created by the electrical signals can interfere with signals in nearby cables, reducing signal quality.

Resistance and Capacitance:

The resistance and capacitance of the copper cable limit how fast signals can change and be reliably transmitted, especially at higher frequencies and longer distances.

Limited Range:

Due to these factors, copper cables have a limited effective range, typically up to 100 meters for standard Ethernet applications.

Repeaters:

To extend the signal's reach beyond its limited range, amplifiers or repeaters are needed to boost the signal strength.

pure copper (Cu)

Despite competition from other materials, copper remains the preferred electrical conductor in nearly all categories of electrical wiring except overhead electric power transmission where aluminium is often preferred.[102][103]
Copper wire is used in power generation, power transmission, power distribution, telecommunications, electronics circuitry, and countless types of electrical equipment.[104] Electrical wiring is the most important market for the copper industry.[105] This includes structural power wiring, power distribution cable, appliance wire, communications cable, automotive wire and cable, and magnet wire. Roughly half of all copper mined is used for electrical wire and cable conductors.[106]
Many electrical devices rely on copper wiring because of its multitude of inherent beneficial properties, such as its high electrical conductivity, tensile strength, ductility, creep (deformation) resistance, corrosion resistance, low thermal expansion, high thermal conductivity, ease of soldering, malleability, and ease of installation.
For a short period from the late 1960s to the late 1970s, copper wiring was replaced by aluminium wiring in many housing construction projects in America. The new wiring was implicated in a number of house fires and the industry returned to copper.[107]

copper beryllium alloy

Beryllium copper is a ductile, weldable, and machinable alloy.
Like pure copper, it is resistant to non-oxidizing acids like hydrochloric acid and carbonic acid, to plastic decomposition products, to abrasive wear, and to galling.
It can be heat-treated for increased strength, durability, and electrical conductivity.
Beryllium copper attains the greatest strength of any copper-based alloy.[1]
It has good thermal conductivity 3-5 times more than tool steel.
It has a solid melting point of 866 °C and 982 °C liquid melting point.
It has an excellent capacity for being hot formed.
C17200 Copper has the strength and hardness similar to that of steel and Rockwell hardness properties in its peaked age condition are in the range of 200 ksi and RC45.
C17200 has excellent corrosion resistant properties when exposed to harsh conditions such as sea water, and down-hole environments.
It will withstand sulfide or chloride stress corrosion cracking, and will resist the effects of carbon dioxide and hydrogen embrittlement.
Copper alloys in general have always been considered non-sparking.
C17200 has the strength to withstand the use of hand and mechanical tools.
These non-sparking features are best applied in explosive environments such as in the Oil & Gas and gun powder industries.[2]

copper cadmium alloy

Pure unalloyed copper is soft and ductile, and usually contains approximately 0.7% impurities.
Cadmium copper alloys are considered high copper alloys, they contain approximately 98 - 99 % copper, 0.1 - 1.5% cadmium and sometimes minor amounts of other materials.
When cadmium is added to copper the material becomes more resistant to softening at elevated temperatures.
The more cadmium that is added the more heat resistant the material becomes.
Small additions of cadmium do not affect the thermal and electrical conductivities, and room temperature mechanical properties of cadmium copper.
Cadmium copper is used in applications such as trolley wire, heating pads, electric blanket elements, spring contacts, connectors, and high strength transmission lines.
Cadmium copper is used for trolley wire because it is extremely resistant to arc erosion.
An extremely heat resistant cadmium oxide forms on the surface of the wire during arcing and protects it from eroding. This enables the cadmium copper wire to retain its strength under the high temperature conditions of the electric trains.
It is also used for soldering applications, particularly to join components in automobile and truck radiators and semi conductor packaging operations. The UNS alloy designations for cadmium copper alloys containing approximately 1% cadmium are C16200 and C16500. An alloy containing 0.1 to 0.2% cadmium is designated as C14300. There are no cast cadmium copper alloys.

copper zinc alloy (brass)

Copper-zinc alloys (brasses)

- Cartridge brass with 70% copper 30% zine is soft and ductile and can be

Severely cold worked - used for the production of cartridge and shell cases, tubes, wire, sheet, deep drawing products.

- High tensile brass (or Muntz metal) has 60% copper and 40% zine and is used for marine propellers, shafts and pumps because of its high tensile strength of about 380 MPa.

structure/property relationships and their application

semiconductors such as transistors, zener diodes, light emitting diodes and laser diodes

A semiconductor is a material that isn’t as good at carrying electricity as a metal, but it’s not completely useless like an insulator either. It sits in between, which is why it’s called a “semi” conductor.

Here’s the trick: we can control how well a semiconductor conducts electricity. By adding tiny amounts of other elements (called doping) or by applying electricity/light, we can make it behave more like a conductor or more like an insulator.

This controllability is what makes semiconductors the foundation of modern electronics. Inside your phone or laptop, billions of tiny switches called transistors are made from semiconductors. These switches turn on and off extremely fast, representing 1s and 0s in digital logic. That’s how all computing happens—at the most basic level, it’s just a ton of semiconductors controlling the flow of electricity.

Think of it like this: metals are like doors that are always open, insulators are doors that are locked shut, and semiconductors are doors with a smart lock—you decide when they open or close.

Resistors

Current increases when resistance increases
Ensure current flow at the appropriate level

Cells & Batteries

Purpose is to supply energy to the circuit in the from of electrons
Coverts chemical energy into electrical energy

Switches

control the flow of an eletrical current in a circuit
makes and break the circuit

Capacitors

Creates backlog of electcity to ensure even flow
Can block DC, but allow AC through

Protection Device

Current and voltage sensitive decvie that protects against overcurrent or over volatge conditions
inrterupts the current flow when a fault is detected

Transformers*

Two coils are placed next to each (primary and secondary)
Transmit electricity from one circuit to another by either stepping up ro stepping down the voltage

Diodes

A semiconductor device that acts as a one way switch
Can also act as a rectifier

Rectifier*

transforms AC current in DC current
uses a series of diodes, as they only allow electyricty to move in one direction
capacitors can also be incoroprated to ensure even DC flow

Voltage Regulators

Automatically maintains voltage across a system
Simpled feedforward design to inhibit eletron flow moving in undesirbale direction (Surge protector)

Transistors*

minitutrized semidconductor that regulates the flow or intensity of the current
can also generate an eletrical signal
can be used to create logic gates, used in IC

Integrated Circuits

electronic circuit integrated into a semicondcuting material
performs same function as larger circuits

Transistors

uses in telecommunications

polymers

insulation materials

Polymers have low electrical conductivity and low thermal conductivity due to the electrons being tightly bound in the primary bonds. However some polymers can be doped with additives which increase conductivity to near that of metals, as well as behave as semi-conductors.
Compared with metals, polymers generally expand more when there is a change in temperature, are generally more corrosion resistant, have lower stiffness, are generally more ductile, have lower hardness and tend to have higher creep values.
A dielectric is an electrical insulator, or poor conductor, that can be polarised by an applied electric field. Unlike conductors, dielectrics have very few free charges, but when an electric field is applied, their internal charges shift, creating an electric dipole and reducing the field within the material. This property allows dielectrics to store electrical energy and increase the capacitance of devices like capacitors.

polymers for telecom cabling — what to choose and why

what matters

Electrical: dielectric constant (lower is better for high-frequency signals), dissipation factor (lower loss), dielectric strength.
Thermal & chemical: continuous temperature rating, UV/chemical resistance.
- Fire safety: smoke density, acidity/halogens, flame spread (common tests below).
- Mechanical: toughness, abrasion/flex life (important for jumpers, patch leads).
- Context: indoor public spaces often require LSZH; outdoor RF feeders need UV and temperature performance; high-freq coax favors very low-loss dielectrics.

quick compare (insulations/jackets you’ll actually see)

Use these as one-liners in responses: requirement → property → named polymer.

PVC (general purpose): economical; easy to process; higher smoke & HCl if it burns. Use where LSZH not required.
PE / XLPE (polyethylene; cross-linked for heat): very low loss, good dielectric strength; XLPE boosts thermal rating. Typical for data pairs, RF dielectrics, outdoor use.
PTFE (“Teflon”): wide service temp, chemically inert; premium choice for high-freq coax and harsh environments.
FEP (fluoropolymer like PTFE, melt-processable): low power factor, high dielectric strength; used in plenum-rated LAN/coax and thin RF cables.
ETFE/“Tefzel”: tough with good electricals; used where abrasion and impact matter.
LSZH jackets (compound class, often polyolefin): designed for low smoke and zero halogen; specify by tests, not by name alone (see below). Ideal for tunnels, stations, schools.

fire & smoke tests you can name (use in justifications)

IEC 60332-1/-3: flame propagation on single/bunched cables.
IEC 60754-1/-2: halogen acid gas; measures acidity/corrosivity of gases.
IEC 61034-1/-2: smoke density (optical).

LSZH stands for Low Smoke Zero Halogen and refers to cable jacketing materials designed to emit minimal smoke and no halogen gases when exposed to high heat, making them a safer choice in fires compared to traditional cables like PVC. This type of cable is crucial in public buildings, airports, and other critical infrastructure where visibility and air quality are essential for safe evacuation.

XLPE stands for Cross-Linked Polyethylene, a form of polyethylene that undergoes a process to create stronger, more durable molecular bonds. This thermosetting polymer boasts superior mechanical strength, improved heat resistance (handling higher temperatures than traditional PVC), and excellent resistance to moisture, chemicals, and abrasion. Due to these qualities, it's widely used as an insulator for high-voltage electrical cables and in various applications like radiant heating systems, water pipes, and even baby mats.

- fibre optics

telecommunications — fibre‑optic materials

Fiber optic cables: How they work (YouTube)

1) outcomes you can hit here

H1.2 differentiate properties/structure of materials and justify selection.

H2.2 analyse/synthesise applications and importance to society.

2) what an optical fibre is (materials & structure)

Core (silica doped to raise index, e.g. Ge‑doped) + cladding (lower‑index silica, often F‑doped) → total internal reflection guides light.

In fiber optics, the core of the fiber is usually made of ultra-pure silica glass, and to tweak its optical properties, you dope it with different materials. For example, adding germanium, increases the refractive index of the core. That helps guide the light more effectively. You might also see fluorine or phosphorus used in the cladding or in the core to lower the refractive index or to fine-tune other characteristics. In other words, these dopants let you shape the fiber’s performance for different applications, like making it more suitable for long-distance transmission or more resistant to bending losses.

Primary/secondary coating: UV‑cured acrylate (sometimes polyimide for high temp) protects glass; not part of light guidance.

So when it comes to those coatings, UV-cured acrylate is a really common material. Basically, the primary coating that goes directly onto the fiber is often this UV-cured acrylate resin. It’s a kind of plastic that stays liquid until you hit it with ultraviolet light, and then it instantly hardens into a protective layer.

The nice thing about using UV-cured acrylate is that it’s super efficient in manufacturing. You just run the fiber through the coating material, zap it with UV light, and boom, you’ve got a nice, durable, flexible coating that protects the fiber from micro-bends and environmental damage. It’s kind of the industry standard because it’s reliable, easy to apply, and does a great job of giving the fiber that first layer of protection.

3) types you should name (and when to pick them) (⬅️ linked)

Single‑mode (SMF) (≈9 µm core): long‑haul, metro, FTTH, backbones; lowest attenuation & dispersion. Transmission Distance of 2 - 120 Km

Bend‑insensitive SMF: tighter bend radius (drop cables, MDU/FTTx).

Multimode (MMF) (50/62.5 µm): short‑reach LANs; graded‑index reduces modal dispersion at 850 nm (VCSEL) modern system use lasers now, originals ones used LED but could not keep up with the modulation. Transmission Distance of 550m

4) the three wavelength “windows” - sweet spots

850 nm (MMF LAN), data centres or building, more attenuation.

At 850 nanometers, you’re generally in the realm of multimode fiber. This wavelength is used a lot in shorter-distance, lower-cost systems—think inside data centers or buildings. The components for 850 nanometer systems are typically cheaper, but the signal doesn’t travel as far because there’s more dispersion and attenuation.

1310 nm (zero‑dispersion region for G.652).

Then at 1310 nanometers, you get into what we call the “zero-dispersion” region for standard single-mode fiber. Signals at 1310 nanometers can travel longer distances than at 850 before dispersion becomes an issue. It’s a nice balance of decent performance and not too much attenuation, and it’s used a lot in metro networks and longer links.

1550 nm (lowest loss; long‑haul; WDM).

1550 nanometers is the go-to for really long-haul communication and undersea cables. The fiber attenuation is at its lowest around 1550 nanometers, which means you can send signals over really long distances with minimal loss. This wavelength is also great for dense wavelength-division multiplexing, where you cram lots of channels together. The downside is the equipment can be a bit more expensive and you’re dealing with single-mode fiber only.

5) loss & dispersion (what markers to quote)

Attenuation (dB/km):

Absorption: The glass material itself isn’t perfectly transparent—there are always tiny impurities or intrinsic properties of the silica that soak up a bit of the light energy and turn it into heat.

Scattering: Think of it like light bumping into tiny irregularities or density variations in the glass, causing it to scatter in different directions. This is called Rayleigh scattering, and it’s a big reason why shorter wavelengths lose more power—because they scatter more easily.

Bending loss: If the fiber is curved or not perfectly straight, some of the light can leak out of the core. That’s more of a mechanical design thing, but it adds to the total attenuation.

6) connectors & splices

Fusion splice: the gold standard when you want a really low-loss, permanent connection. It’s like welding two pieces of fiber together. You align the fiber ends super precisely, then use an electric arc to literally fuse them into one continuous piece of glass. The result is a very low insertion loss and high reliability, but it’s a permanent joint. Once you fuse it, you’re not unplugging it.

Connector pair: more like plug-and-play solutions. You put a connector on the end of each fiber so you can easily connect and disconnect them. That’s great for flexibility, like if you need to reconfigure things or swap out equipment. The trade-off is you get a bit more insertion loss than with a fusion splice, and there’s a little more reflection at the connection point. But for many applications, that’s a small price to pay for the convenience.

types and applications

materials

Zoom into a Microchip video | NISE NetworkThis zoom video explores the inner-wo

Microchips

This zoom video explores the inner-workings of a microchip. We start with a digital camera and transition to a scanning electron microscope. You'll see the tiny wires and the crisscrossing patterns of the microchip's circuits while learning a bit about why making it small is important.

2021 - Question 26 (c)

2021 - Question 26 (d)

2022 - Question 27 (a)

2022 - Question 22 (c)

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