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Cert III Electrician practice questions

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Question 1Workplace safety, WHS obligations and environmental practices

Under Australian WHS law, what is the primary duty of a person conducting a business or undertaking (PCBU)?

  1. To report every near miss to the regulator within 24 hours
  2. To provide workers with a copy of the WHS Act at the start of each shift
  3. To ensure the health and safety of workers and others affected by the work, so far as is reasonably practicable Correct answer.
  4. To appoint an external safety consultant for all high-risk work

Explanation

The primary duty of care requires a PCBU to eliminate or minimise risks to the health and safety of workers and other persons affected by the business, so far as is reasonably practicable. This duty is broad and cannot be transferred to another party, although other duty holders also have their own obligations.

Question 2Workplace safety, WHS obligations and environmental practices

A worker is directed to work near live low-voltage conductors. Which statement best reflects the hierarchy of control for electrical work?

  1. Rubber gloves alone make live work acceptable in all circumstances
  2. Live work is acceptable if a second person watches from a distance
  3. Live work is permitted whenever the worker holds a current electrical licence
  4. De-energising and isolating the circuit is the preferred control, with live work used only where justified Correct answer.

Explanation

The hierarchy of control requires the highest-order control that is reasonably practicable, which for electrical work means de-energising and proving dead before work begins. Live work should only proceed where it is not reasonably practicable to isolate and where a documented risk assessment supports it.

Question 3Workplace safety, WHS obligations and environmental practices

Which incident must a PCBU notify to the WHS regulator immediately after becoming aware of it?

  1. A worker spraining an ankle while walking to the site shed
  2. A worker sustaining a serious injury requiring immediate hospital admission as an inpatient Correct answer.
  3. A worker developing mild dermatitis after several weeks
  4. A worker cutting a finger that is treated with a bandage on site

Explanation

Notifiable incidents include a death, a serious injury or illness, or a dangerous incident. A serious injury includes one requiring immediate treatment as an inpatient in a hospital, which must be reported to the regulator immediately.

Question 4Workplace safety, WHS obligations and environmental practices

A worker notices a damaged extension lead with exposed inner conductors on a construction site. What is the most appropriate immediate action?

  1. Continue using it if the work is short and the area is dry
  2. Tag it out of service, remove it from use, and report the defect Correct answer.
  3. Wrap the damaged section with insulation tape and keep using it
  4. Move it to another area so other workers are not exposed

Explanation

Damaged electrical equipment must be withdrawn from service immediately, tagged as defective, and reported so it can be repaired or replaced. Continuing to use it, or merely relocating it, leaves a live electrical hazard for others.

Question 5Workplace safety, WHS obligations and environmental practices

What is the main purpose of a Safe Work Method Statement (SWMS) for high-risk construction work?

  1. To document the client's budget for the project
  2. To record the qualifications of each worker on site
  3. To describe how the high-risk work will be carried out and the controls that will manage the risks Correct answer.
  4. To replace the need for a site-specific risk assessment

Explanation

A SWMS sets out the type of high-risk work, the hazards involved, and the control measures that will be applied, and it must be reviewed and monitored. It documents how the work will be done safely rather than serving administrative or financial purposes.

Question 6Workplace safety, WHS obligations and environmental practices

A worker is required to work at height on a ladder for a short electrical task. Which control should be applied first according to the hierarchy of control?

  1. Perform the task from ground level or a stable platform if reasonably practicable Correct answer.
  2. Ask a co-worker to hold the base of the ladder
  3. Provide fall-arrest harness training to the worker
  4. Use a ladder because it is quick and portable

Explanation

The hierarchy requires eliminating the need to work at height where reasonably practicable, for example by completing the task from ground level. Where elimination is not possible, higher-order controls such as a stable platform or guardrails are preferred over ladders and harnesses.

Question 7Workplace safety, WHS obligations and environmental practices

What does the term 'reasonably practicable' require a PCBU to weigh up?

  1. Whether the worker has signed a safety declaration
  2. Only the cost of any control measure
  3. The likelihood and severity of harm against what is known about the hazard and the cost and availability of controls Correct answer.
  4. The number of years a worker has been employed

Explanation

Reasonably practicable involves balancing the likelihood and degree of harm against what the duty holder knows or ought to know about the hazard and the ways to eliminate or minimise it, including cost. It is an objective test, not a simple cost decision.

Question 8Workplace safety, WHS obligations and environmental practices

A worker receives a minor electric shock from a portable tool but is not injured. What should the worker do?

  1. Report the incident and have the tool inspected before further use Correct answer.
  2. Say nothing because no injury occurred
  3. Continue using the tool but wear thicker gloves
  4. Place the tool in the toolbox for use on another site

Explanation

Even without injury, an electric shock is a dangerous incident that must be reported internally and investigated, and the equipment should be withdrawn and inspected. Concealing it allows a faulty tool to injure someone else.

Question 9Workplace safety, WHS obligations and environmental practices

Which of the following best describes the role of a Health and Safety Representative (HSR)?

  1. To issue on-the-spot fines to workers who breach safety rules
  2. To represent workers in their work group on WHS matters and raise issues with the PCBU Correct answer.
  3. To take over the PCBU's duty of care for the work group
  4. To conduct the regulator's incident investigations

Explanation

An HSR is elected by workers in a work group to represent them on health and safety matters and to consult with the PCBU. HSRs have powers such as requesting information and issuing provisional improvement notices, but they do not take over the PCBU's duties.

Question 10Workplace safety, WHS obligations and environmental practices

A worker is asked to enter a confined space to install conduit. Which requirement applies before entry?

  1. The space is ventilated only after the worker enters
  2. The worker signs a waiver accepting the risks
  3. A torch is provided for visibility
  4. An entry permit and atmospheric testing are completed and controls are in place Correct answer.

Explanation

Confined space entry requires a risk assessment, an entry permit, atmospheric testing, isolation, and standby arrangements before anyone enters. These controls must be in place before entry, not after.

Question 11Workplace safety, WHS obligations and environmental practices

What is the correct action when a worker identifies an uncontrolled hazard that poses an immediate risk to life?

  1. Ignore it because it is outside the worker's trade
  2. Stop work, make the area safe, and notify the supervisor immediately Correct answer.
  3. Record the hazard in the site diary at the end of the week
  4. Continue working until the supervisor returns from lunch

Explanation

Workers have the right to cease unsafe work and must stop when there is an immediate risk to health or safety. The area should be made safe and the matter escalated to the supervisor or PCBU immediately.

Question 12Workplace safety, WHS obligations and environmental practices

Which practice best manages environmental risk when disposing of waste from an electrical installation?

  1. Separating recyclable materials such as copper and cable offcuts and disposing of them through appropriate recycling streams Correct answer.
  2. Burning cable offcuts on site to reduce volume
  3. Placing all waste in the general rubbish bin
  4. Leaving waste on site for the client to remove

Explanation

Environmental duty requires waste to be segregated and managed so that recyclable materials such as copper and cable are diverted from landfill. Burning waste or abandoning it causes pollution and breaches environmental obligations.

Question 13Workplace safety, WHS obligations and environmental practices

A worker is using a generator on site. Which control reduces the risk of carbon monoxide exposure?

  1. Locating the generator outdoors in a well-ventilated area away from air intakes Correct answer.
  2. Operating the generator inside a closed room to reduce noise
  3. Running the generator only when workers are sleeping on site
  4. Placing the generator near the workers so they can monitor it

Explanation

Petrol and diesel generators produce carbon monoxide, so they must be operated outdoors in a well-ventilated location away from windows and air intakes. Enclosed spaces allow the gas to accumulate to lethal levels.

Question 14Workplace safety, WHS obligations and environmental practices

What information does a Safety Data Sheet (SDS) provide to a worker using a chemical product?

  1. The client's preferred brand of the product
  2. The names of other workers who have used the product
  3. The purchase price and supplier discounts
  4. The hazards, safe handling, PPE, and first-aid measures for the product Correct answer.

Explanation

An SDS provides information on the hazards, safe handling, storage, exposure controls, and first-aid measures for a hazardous chemical. It is a key reference for assessing risk and selecting controls before use.

Question 15Workplace safety, WHS obligations and environmental practices

Which of the following is the best example of a higher-order control for reducing manual handling risk when installing a heavy switchboard?

  1. Using a mechanical hoist or trolley to move the switchboard Correct answer.
  2. Rotating workers every hour
  3. Providing back braces to workers
  4. Training workers in correct lifting technique

Explanation

Engineering controls such as hoists and trolleys remove or reduce the physical demand and are higher in the hierarchy than administrative controls or PPE. Training and rotation rely on worker behaviour and do not eliminate the load.

Question 16Workplace safety, WHS obligations and environmental practices

What is the purpose of lock-out/tag-out (LOTO) during electrical maintenance?

  1. To identify which worker owns each tool
  2. To indicate that the equipment is ready for use
  3. To record the time each worker spends on the task
  4. To prevent the unexpected energisation or release of energy while work is being carried out Correct answer.

Explanation

LOTO isolates energy sources and applies locks and tags so equipment cannot be re-energised while maintenance is underway. Each worker applies their own lock, and the equipment is proven dead before work starts.

Question 17Workplace safety, WHS obligations and environmental practices

A worker is exposed to high noise levels while using a core drill. What is the correct order of control?

  1. Rely on hearing protection alone
  2. Rotate workers so each is exposed for less time only
  3. Reduce noise at the source or use quieter equipment, then use administrative controls, then hearing protection Correct answer.
  4. Provide earplugs first, then consider quieter equipment

Explanation

The hierarchy of control requires noise to be reduced at the source where practicable, followed by administrative controls and finally PPE such as hearing protection. PPE is the last line of defence and should not be the sole control.

Question 18Workplace safety, WHS obligations and environmental practices

Which statement about the right to refuse unsafe work is correct?

  1. A worker can be dismissed for refusing work they believe is unsafe without any discussion
  2. Only supervisors have the right to stop unsafe work
  3. A worker may cease work if they have a reasonable concern about an immediate risk, and must notify the PCBU Correct answer.
  4. A worker must continue working until the regulator attends the site

Explanation

Workers have the right to cease unsafe work where they have a reasonable concern of an immediate risk to health or safety, and they must notify the PCBU as soon as practicable. They must remain available for suitable alternative work.

Question 19Workplace safety, WHS obligations and environmental practices

A PCBU must consult with workers on WHS matters. Which situation best demonstrates meaningful consultation?

  1. Posting a safety notice on the noticeboard after a decision is made
  2. Discussing proposed changes to work procedures with workers and considering their views before deciding Correct answer.
  3. A toolbox talk delivered without opportunity for questions
  4. Emails sent to workers informing them of a decision already implemented

Explanation

Consultation requires sharing relevant information, giving workers a reasonable opportunity to express views, and taking those views into account before a decision is made. Informing workers after the fact is not consultation.

Question 20Workplace safety, WHS obligations and environmental practices

Which of the following is a dangerous incident that must be reported to the regulator even if no one is injured?

  1. A toolbox talk being cancelled
  2. A worker arriving late for a shift
  3. An electrical short circuit that causes a fire or explosion in the workplace Correct answer.
  4. A worker losing their safety glasses

Explanation

A dangerous incident includes an uncontrolled escape of electricity, a fire or explosion, or a structural collapse that exposes a person to serious risk. These must be reported even when no injury results.

Question 21Workplace safety, WHS obligations and environmental practices

A worker is asked to work alone on a remote switchboard installation. Which control most directly addresses the risk of an incapacitating electric shock?

  1. Scheduling the work for a Friday afternoon
  2. Providing a mobile phone with a full battery
  3. Establishing a means of regular contact and a rescue or emergency response arrangement Correct answer.
  4. Providing the worker with a second set of gloves

Explanation

Lone work requires arrangements for regular contact and a documented emergency response so that an injured worker can be found and assisted. A phone alone is insufficient without a monitoring and rescue plan.

Question 22Workplace safety, WHS obligations and environmental practices

Which action best demonstrates the environmental duty to prevent pollution from an electrical contractor's activities?

  1. Pouring used oil onto the ground away from the building
  2. Storing chemicals in unlabelled containers near a drain
  3. Containing and disposing of washout and chemical waste through approved waste contractors Correct answer.
  4. Washing concrete dust and solvent residue into the stormwater drain

Explanation

Pollution prevention requires containing waste and chemicals and disposing of them through approved channels so they cannot enter stormwater or soil. Unlabelled storage and discharge to drains create a risk of environmental harm and regulatory breach.

Question 23Workplace safety, WHS obligations and environmental practices

What is the main function of a Job Safety Analysis (JSA) or pre-start risk assessment?

  1. To calculate the labour cost of the task
  2. To record the worker's employment history
  3. To identify the hazards of a specific task and the controls to be applied before work starts Correct answer.
  4. To replace the need for consultation with workers

Explanation

A JSA breaks a task into steps, identifies the hazards at each step, and documents the controls to be used. It is completed before work begins and should involve the workers who will perform the task.

Question 24Workplace safety, WHS obligations and environmental practices

A worker is using a portable RCD on a construction site. What is its purpose?

  1. To increase the current available to the tool
  2. To convert AC power to DC power
  3. To measure the voltage of the circuit
  4. To disconnect the supply quickly if a fault current to earth is detected Correct answer.

Explanation

A residual current device monitors the current in the active and neutral conductors and trips when it detects a difference indicating leakage to earth. This limits the duration of a shock and reduces the risk of serious injury.

Question 25Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

In a simple series circuit containing a 12 V battery and two resistors of 3 Ω and 6 Ω, what current flows through the circuit?

  1. 2 A
  2. 4 A
  3. 1.33 A Correct answer.
  4. 0.75 A

Explanation

In a series circuit the resistances add, giving 9 Ω total. Ohm's law then gives I = V/R = 12/9 = 1.33 A, and this same current passes through every series element.

Question 26Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Two resistors, 4 Ω and 12 Ω, are connected in parallel across a 24 V supply. What is the total current drawn from the supply?

  1. 8 A Correct answer.
  2. 6 A
  3. 1.5 A
  4. 2 A

Explanation

In parallel each branch sees the full 24 V, so branch currents are 24/4 = 6 A and 24/12 = 2 A. Kirchhoff's current law adds them, giving 8 A total. Equivalently the equivalent resistance is 3 Ω.

Question 27Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Which statement correctly describes the magnetic field produced by a straight current-carrying conductor?

  1. The field lines run parallel to the conductor and increase with distance from it.
  2. The field is confined entirely inside the conductor material.
  3. The field direction is independent of the direction of current flow.
  4. The field lines form concentric circles around the conductor, weakening with distance. Correct answer.

Explanation

Current in a straight conductor produces a magnetic field whose lines are concentric circles around the wire. The field strength falls off with increasing radial distance, and reversing the current reverses the field direction.

Question 28Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A coil of wire is rotated steadily inside a uniform magnetic field. What is the principal effect on the conductor?

  1. A constant DC voltage independent of rotation angle is induced.
  2. No voltage is induced because the coil is closed.
  3. The magnetic field is destroyed by the rotation.
  4. An alternating EMF is induced as the flux linkage changes. Correct answer.

Explanation

Faraday's law states that an EMF is induced whenever the magnetic flux linking a circuit changes. Rotating the coil continuously changes the flux linkage sinusoidally, so the induced EMF alternates in polarity and magnitude.

Question 29Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

What is the RMS value of a sinusoidal voltage whose peak value is 339 V?

  1. 678 V
  2. 240 V Correct answer.
  3. 170 V
  4. 480 V

Explanation

For a sine wave, RMS value equals peak value divided by the square root of two. Dividing 339 V by 1.414 gives approximately 240 V, the standard nominal supply value.

Question 30Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Which instrument connection is correct for measuring the current through a load?

  1. An ammeter connected in series with the load Correct answer.
  2. An ammeter connected in parallel with the load
  3. A voltmeter connected in parallel across the supply only
  4. A voltmeter connected in series with the load

Explanation

An ammeter must carry the load current, so it is connected in series and has very low resistance. A voltmeter is connected in parallel and has very high resistance to avoid drawing significant current.

Question 31Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A 100 Ω resistor dissipates 4 W. What current flows through it?

  1. 0.04 A
  2. 25 A
  3. 0.2 A Correct answer.
  4. 2 A

Explanation

Power in a resistor is P = I²R, so I = square root of (P/R) = square root of (4/100) = square root of 0.04 = 0.2 A. The voltage across it would then be 20 V.

Question 32Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

In a purely capacitive AC circuit, how does the current relate to the applied voltage?

  1. Current lags the voltage by 90 degrees.
  2. Current is 180 degrees out of phase with the voltage.
  3. Current is exactly in phase with the voltage.
  4. Current leads the voltage by 90 degrees. Correct answer.

Explanation

In a capacitor, current reaches its maximum before the voltage does, so current leads voltage by a quarter cycle, or 90 degrees. This phase relationship produces purely reactive power with no net energy dissipation.

Question 33Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A transformer has 500 primary turns and 50 secondary turns. If the primary is supplied at 240 V AC, what is the secondary voltage (ignoring losses)?

  1. 2400 V
  2. 48 V
  3. 24 V Correct answer.
  4. 120 V

Explanation

The turns ratio equals the voltage ratio: Vp/Vs = Np/Ns. Here the ratio is 500/50 = 10, so the secondary voltage is 240/10 = 24 V. This is a step-down transformer.

Question 34Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Which material property best explains why a ferromagnetic core concentrates magnetic flux?

  1. Its low melting point allows tighter winding.
  2. Its high permittivity stores electric charge.
  3. Its high permeability provides an easy path for flux. Correct answer.
  4. Its high electrical resistivity limits eddy currents.

Explanation

Ferromagnetic materials such as iron have high permeability, so flux lines preferentially follow them rather than air. This concentrates and strengthens the field within the core, which is why iron cores are used in transformers and electromagnets.

Question 35Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A conductor carries 5 A and lies perpendicular to a uniform magnetic field of 0.4 T. If 0.5 m of conductor is within the field, what force acts on it?

  1. 1.0 N Correct answer.
  2. 0.1 N
  3. 0.04 N
  4. 2.0 N

Explanation

The force on a current-carrying conductor is F = B I L when the conductor is perpendicular to the field. Substituting gives 0.4 × 5 × 0.5 = 1.0 N.

Question 36Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Which change increases the capacitance of a parallel-plate capacitor?

  1. Inserting a dielectric of higher permittivity Correct answer.
  2. Reducing the area of the plates
  3. Removing the dielectric material entirely
  4. Increasing the separation between the plates

Explanation

Capacitance is proportional to plate area and permittivity, and inversely proportional to plate separation. Inserting a dielectric with higher permittivity therefore increases capacitance for the same physical dimensions.

Question 37Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

An AC circuit has a resistance of 8 Ω and an inductive reactance of 6 Ω in series. What is the impedance?

  1. 48 Ω
  2. 10 Ω Correct answer.
  3. 2 Ω
  4. 14 Ω

Explanation

Resistance and reactance are 90 degrees out of phase, so they add vectorially: Z = square root of (R² + X²) = square root of (64 + 36) = 10 Ω. Simple arithmetic addition would incorrectly give 14 Ω.

Question 38Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

According to Kirchhoff's voltage law, what is true for any closed loop in a circuit?

  1. The voltage drops always sum to the supply voltage regardless of direction.
  2. The total resistance around the loop equals the total current.
  3. The algebraic sum of the voltage drops around the loop equals zero. Correct answer.
  4. The sum of the currents entering each node equals zero.

Explanation

Kirchhoff's voltage law states that the algebraic sum of potential differences around any closed loop is zero, reflecting energy conservation. Signs must be assigned consistently to rises and drops as the loop is traversed.

Question 39Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

What is the frequency of an AC waveform that completes one cycle in 20 milliseconds?

  1. 20 Hz
  2. 5 Hz
  3. 500 Hz
  4. 50 Hz Correct answer.

Explanation

Frequency is the reciprocal of the period: f = 1/T. With T = 0.020 s, f = 1/0.020 = 50 Hz, the standard mains frequency in many countries.

Question 40Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A 12 V battery is connected to a series circuit of 2 Ω, 3 Ω and 7 Ω. What is the voltage across the 7 Ω resistor?

  1. 3 V
  2. 7 V Correct answer.
  3. 5 V
  4. 12 V

Explanation

Total resistance is 12 Ω, so the current is 12/12 = 1 A. The voltage across the 7 Ω resistor is V = IR = 1 × 7 = 7 V, illustrating the voltage divider principle.

Question 41Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Which effect explains why a changing current in one coil induces a voltage in a nearby separate coil?

  1. Self-inductance within the first coil only
  2. Electrostatic induction between the windings
  3. Mutual inductance through the shared magnetic field Correct answer.
  4. Capacitive coupling between adjacent turns

Explanation

A changing current in the primary produces a changing magnetic field that links the secondary coil. This mutual inductance induces an EMF in the secondary, the principle behind transformers.

Question 42Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A resistor of 20 Ω and an inductor with reactance 20 Ω are in series across 100 V AC. What is the phase angle between voltage and current?

  1. 90 degrees
  2. 30 degrees
  3. 60 degrees
  4. 45 degrees Correct answer.

Explanation

The phase angle is given by tan θ = X/R. With X = R = 20 Ω, tan θ = 1, so θ = 45 degrees. Current lags the voltage by this angle because the circuit is inductive.

Question 43Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

What is the purpose of laminating the core of an AC machine?

  1. To increase the magnetic flux density in the core
  2. To reduce eddy current losses Correct answer.
  3. To increase the core's electrical resistance to magnetic flux
  4. To decrease the number of turns required

Explanation

Laminations are thin insulated sheets that interrupt the paths available for circulating eddy currents. This greatly reduces eddy current heating losses in the core while still allowing magnetic flux to pass.

Question 44Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

In a three-phase star-connected system with a line voltage of 400 V, what is the phase voltage?

  1. 400 V
  2. 230 V Correct answer.
  3. 200 V
  4. 693 V

Explanation

In a star connection the phase voltage is the line voltage divided by the square root of three. Dividing 400 V by 1.732 gives approximately 231 V, commonly quoted as 230 V.

Question 45Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A moving-coil meter is used to measure an AC waveform. What does it display?

  1. The average value of the rectified waveform Correct answer.
  2. The instantaneous value at every moment
  3. The peak value of the waveform
  4. The RMS value of the waveform

Explanation

A moving-coil movement responds to average current, so with a rectifier it reads the average of the rectified waveform. The scale is usually marked to show the equivalent RMS value for a sine wave, assuming a pure sine input.

Question 46Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Which statement correctly describes conventional current direction?

  1. It flows in the same direction as electron flow.
  2. It always flows toward the lowest resistance path.
  3. It flows from negative to positive, opposite to electron flow.
  4. It flows from positive to negative, opposite to electron flow. Correct answer.

Explanation

Conventional current is defined as flowing from the positive terminal through the external circuit to the negative terminal. Electrons actually drift in the opposite direction, from negative to positive.

Question 47Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

A 230 V AC supply feeds a load drawing 10 A at a power factor of 0.8. What is the real power consumed?

  1. 230 W
  2. 2300 W
  3. 2875 W
  4. 1840 W Correct answer.

Explanation

Real power equals voltage times current times power factor: P = VI cos φ. Substituting gives 230 × 10 × 0.8 = 1840 W, while the apparent power is 2300 VA.

Question 48Electrical fundamentals: circuits, magnetism, AC/DC theory and measurements

Two 6 Ω resistors are connected in parallel. What is the equivalent resistance?

  1. 3 Ω Correct answer.
  2. 6 Ω
  3. 1.5 Ω
  4. 12 Ω

Explanation

For two equal resistors in parallel, the equivalent resistance is half of one value: 6/2 = 3 Ω. The general formula 1/R = 1/6 + 1/6 gives the same result.

Question 49Wiring systems, cable selection, protection and installation methods

Which conductor colour is used for the active conductor in a single-phase flexible cord in Australia?

  1. Green/yellow
  2. Blue
  3. Black
  4. Brown Correct answer.

Explanation

In Australian single-phase flexible cords the active is brown, the neutral is blue and the earth is green/yellow. Fixed wiring uses red for active, black for neutral and green/yellow for earth. The brown active convention aligns with international harmonised colours.

Question 50Wiring systems, cable selection, protection and installation methods

What does the first digit of an IP rating such as IP44 indicate?

  1. The maximum ambient temperature rating
  2. Degree of protection against ingress of solid objects Correct answer.
  3. The cable's mechanical impact strength
  4. Degree of protection against water ingress

Explanation

The IP code has two digits: the first rates protection against solid foreign objects and contact, the second rates protection against water. IP44 therefore means protection against objects larger than 1 mm and splashing water. The digits do not relate to temperature or impact.