CITY & GUILDS - ELECTRICAL QWIZDOM MULTIPLE CHOICE PAPER

The role of a company's safety representative is to:

A. represent employees on safety matters.B. be responsible for writing risk assessments.C. represent the company at HSE meetings.D. ensure safety facilities are available.

An electric machine has a power output of 1500 watts. The input current is 4A and the applied voltage is 400V. The efficiency of the machine will be:

A. 50%.B. 75%.C. 87.55%.D. 93.75%.

If a contract is not completed on time the client may enforce a:

A. failure to agree.B. contractual adjustment.C. penalty clause.D. prohibition notice.

The device used to change a.c. to d.c in a d.c. generator called is the:

A. Poles.B. Commutator.C. Slip rings.D. Brushes.

An abnormal amount of carbon dioxide in an enclosed work space may cause:

A. unconsciousness or dizziness.B. watering of the eyes.C. skin irritation.D. injury to the eyes.

A water fire extinguisher has a red body and an indicating rectangle which is :

A. cream.B. blue.C. red.D. black.

Advice on safety matters can be obtained from the :

A. Royal Society for Prevention of Accidents .B. Department of Health .C. Learning and Skills Council .D. Department for Trade and Industry .

In a d.c motor armature, the difference between the applied voltage and the armature voltage drop is

created because of the:

A. slip.B. impedance.C. back emf.D. mutual inductive effect.

The resistivity of a material is defined as the resistance when measured across the opposite faces of a cube of

that material, of volume

• 1m3.• 1 cm3.• 1 mm3.• 1 µm3.

When equipment is deemed to be satisfactory for the job in hand it is described as :

A. performing well .B. able for purpose.C. satisfactory.D. fit for the purpose intended.

The procedure put in place by an employer to identify hazards in the workplace is called a

A. hazard control survey.B. risk assessment procedure.C. safety assessment.D. risk control procedure.

In a capacitor start, single phase, motor the capacitor is connected:

A. across the supply.B. in parallel with the run winding.C. in series with the run winding.D. in series with the start winding.

Safeguarding the rights of individuals with respect to sensitive information is contained in the

A. Health and Safety at Work Act.B. Official Secrets Act.C. Data Protection Act.D. Human Rights Act.

A risk assessment should be carried out

A. before turning on machinery.B. after an accident in the workplace.C. when work activities could put anyone at risk.D. before work commences.

When planning work schedules, a building site manager must:

A. take account of equipment costs.B. take account of tea breaks.C. ensure workers are competent.D. co-ordinate the activities of workers from all

trades.

Supplementary protection against electric shock is provided by a:

A. overcurrent protection device.B. residual current device.C. BS 88 fuse.D. cartridge fuse.

The reactance of a 1µF capacitor connected across a 50Hz supply is:

A. 3.18 kΩ.B. 31.8 kΩ.C. 3.18 mΩ.D. 318 Ω.

Wound rotor induction motors are considered to be:

A. variable speed machines.B. low torque machines.C. constant speed machines.D. low speed machines.

The main function of a fuse is to protect:

A. against voltage ‘spikes’.B. circuit conductors.C. against electric shock.D. the consumer control unit.

The rotor conductors of a three phase cage rotor induction motor take the form of solid conductors:

A. connected to the supply via conductors.B. in series with the rotor windings.C. shorted at each end by rings.D. connected to the supply via slip rings.

If the plates of a parallel plate capacitor are increased in area, the capacitance will:

A. not change.B. increase.C. decrease.D. reduce to zero.

A transistor connected in 'common emitter mode' and biased to cause saturation will act as:

A. an open switch.B. a current amplifier.C. a controlled rectifier.D. a closed switch.

If a pure inductor of reactance 100Ω is connected across a single phase 230 V a.c supply, the power dissipated in the circuit will be:

A. 0W.B. 529 W.C. 2.32 W.D. 23 kW.

Earth leakage currents can occur naturally in electrical equipment, for example, cookers, fridges and freezers.

This can cause nuisance tripping if the system is protected by a:

A. BS 1361 fuse.B. solid state device.C. residual current device.D. cartridge fuse.

Increasing the excitation, to the electromagnet in an a.c. generator will result in:

A. increased output frequency .B. increased back emf.C. reduced voltage output.D. increased output voltage .

Which one of the following correctly lists three losses inherent in a d.c machine :

• Iron, Copper, Friction.• Copper, Friction, Hysteresis.• Current, Voltage, Hysteresis.• Iron, Copper, Magnetic.

The centrifugal switch in a split phase motor is used to

• disconnect the starter at full speed.• disconnect the run winding when approaching

full speed.• disconnect the start winding when

approaching full speed.• disconnect the main supply to the start

winding above full speed.

An electric heater dissipates a power of 3.0 kW when connected to a 230 V a.c. supply. The resistance of the

heater is :

A. 13.0 Ω.B. 15.65 Ω.C. 17.6 Ω.D. 35.2 Ω.

When a semi conductor diode is connected across an a.c. supply having a peak value of 5 V, the peak

inverse voltage across the diode is

A. 2.5 V.B. 3.5 V.C. 5.0 V.D. 7.07 V.

A circuit has a resistance of 20 Ω and an inductive reactance of 15Ω when connected to an a.c. supply.

The impedance of the circuit is :

A. 5.9 ΩB. 25.0 ΩC. 17.3 ΩD. 35.0

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