# Unit 202 Revision: Electrical Science Question Bank 1

### Description

C&G 2365 Unit 202 Smartscreen Sample Qs
Quiz by Oliver Balay, updated more than 1 year ago
 Created by Oliver Balay almost 9 years ago
31547
12

## Resource summary

### Question 1

Question
Electric current is described as a flow of
• protons
• neutrons
• electrons
• nucleus

### Question 2

Question
Which one of the following identifies the sources of an electromotive force?
• Atomic, magnetic, thermal
• Chemical, atomic, thermal
• Chemical, magnetic, thermal
• Chemical, magnetic, atomic

### Question 3

Question
When the current passing through a conductor is increased, the conductor’s temperature will:
• decrease
• stabilise
• fragment
• increase

### Question 4

Question
The SI unit Henry is used for
• capacitance
• inductance
• frequency
• flux density

### Question 5

Question
Ohm is the SI unit of measurement for:
• resistance
• voltage
• current
• charge

### Question 6

Question
The SI unit for frequency is the
• Joule
• Mole
• Hertz

### Question 7

Question
Resistance, potential difference and electrical current are expressed in the same order as units of:
• Ohms, Volts, Amperes
• Ohms, Watts, Amperes
• Ohms, Volts, Watts
• Watts, Volts, Ohms

### Question 8

Question
Transpose the formula Z² = R² + X² to make R² the subject.
• R² = X² – Z²
• R² = Z² – X²
• R² = Z² + X²
• R² = X² x Z²

### Question 9

Question
If the resistivity of aluminium is 2.65 x 10 -8 /metre, the resistance of a 65 metre length of 16mm2 aluminium conductor is:
• 10.77Ω
• 1.108Ω
• 0.0108Ω
• 0.108Ω

### Question 10

Question
For the circuit shown, the total resistance is:
• 108Ω
• 36Ω
• 12Ω
• 3.6Ω

### Question 11

Question
For the circuit shown, the power dissipated by the 15Ω resistor is:
• 240W
• 60W
• 160W
• 40W

### Question 12

Question
The power dissipated in the circuit shown on the right would be:
• 35W
• 833W
• 350W
• 1,399W

### Question 13

Question
When measuring current flow in a d.c. circuit, an ammeter must be connected:
• using a rectifier
• using a VT
• in series with the load
• in parallel with the load

### Question 14

Question
Instrument B in the figure on the right measures the:
• voltage drop caused by R2
• voltage drop caused by R3
• current through R1
• current through R2

### Question 15

Question
The strength of the magnetic flux produced when current flows in a conductor can be increased by:
• increasing the current
• decreasing the current
• reversing the current
• using alternating current

### Question 16

Question
Which one of the following shows the correct poles of the electromagnet when current flows in the direction shown?
• a)
• b)
• c)
• d)

### Question 17

Question
What would be the effect on magnetic flux for the two equal, current-carrying conductors shown?
• The magnetic field would halve in strength, flowing in opposite directions
• The magnetic fields around each of the conductors would rotate independently
• The magnetic fields around the conductors would cancel each other out
• The magnetic field around the conductors would double in strength and flow in the same direction

### Question 18

Question
A conductor of a simple alternator is 0.4m long and cuts a magnetic field with a magnetic flux density of 1.5 tesla at a velocity of 30m/s. The EMF induced in the conductor will be:
• 1,800V
• 180V
• 18V
• 1.8V

### Question 19

Question
Which one of the following is the supply frequency if a sine wave has a periodic time of 20 milliseconds?
• 40Hz
• 50Hz
• 60Hz
• 70Hz

### Question 20

Question
Refer to the figure shown. What does value A indicate?
• Average value of the waveform
• Periodic time of the waveform
• RMS value of the waveform
• Peak amplitude of the waveform

### Question 21

Question
Which one of the following quantities can be described as a force?
• Gravity
• Current
• Resistance
• Energy

### Question 22

Question
The formula shown is used to determine the force required given mass and acceleration. Which one of the following would be the acceleration for a mass of 20kg having a force of 10N applied? F = m x a
• 200 m/s²
• 0.5 m/s²
• 5 m/s²
• 50 m/s²

### Question 23

Question
The power required to raise a mass of 8kg across a distance of 10m in 40 seconds is approximately:
• 785W
• 80W
• 20W
• 5W

### Question 24

Question
A motor produces an output of 1.2kW when the input is 1.4kW; its efficiency is:
• 85.7%
• 75.7%
• 65.7%
• 55.7%

### Question 25

Question
When used to ‘inch’ heavy equipment across the floor, a crowbar is being:
• a pulley
• a lift
• a machine
• a lever

### Question 26

Question
Which one of the following instruments would be used to measure the line voltage for the star connected load?
• A
• B
• C
• D

### Question 27

Question
In a four-wire, three phase system the phase voltage is 220v. The line voltage will be:
• 380V
• 400V
• 415V
• 420V

### Question 28

Question
Which one of the following is the phase voltage for a star connected load if the line voltage is 400V?
• 400V
• 230V
• 110V
• 50V

### Question 29

Question
Which one of the following instruments would be used to measure the line current for the delta connected load?
• A
• B
• C
• D

### Question 30

Question
The line current feeding a delta load is 52A. The delta phase current will be:
• 30A
• 52A
• 90A
• 156A

### Question 31

Question
The phase current in a delta load is 10A. The line current will be:
• 5A
• 5.8A
• 10A
• 17.3A

### Question 32

Question
A balanced three phase star connected load draws a line current of 24A per phase. Which of the following is the approximate value of neutral current?
• 0A
• 8A
• 13.9A
• 24A

### Question 33

Question
A d.c. motor in which the current remains constant in the field winding but varies in the armature winding is called:
• a compound machine
• an armature machine
• a shunt machine
• a series machine

### Question 34

Question
If a single loop of wire connected to a commutator is rotated in a permanent magnetic field, the voltage measured at the commutator will be:
• d.c.
• a.c.
• intermittent
• unidirectional

### Question 35

Question
The diagram shows a simple motor, indicating the field poles and direction of current flow. In which one of the following directions would the conductor move?
• Direction A
• Direction B
• Direction C
• Direction D

### Question 36

Question
In a 400v to 4,000v step-up transformer the ratio of primary to secondary turns ratio will be:
• 10:1
• 5:1
• 1:5
• 1:10

### Question 37

Question
Which one of the following components would cause current and voltage to behave as indicated in the sine wave shown?
• Rectifier
• Capacitor
• Inductor
• Resistor

### Question 38

Question
The power triangle shown gives the relationship between powers in an a.c. circuit. Which one of the following is the unit used to measure Apparent power?
• kW
• kVA
• kVAr
• kJ

### Question 39

Question
A circuit dissipates 3kW at a power factor of 0.7 when connected to a 230V a.c. supply. The current flowing in the circuit will be:
• 13.0A
• 18.6A
• 21.5A
• 25.2A

### Question 40

Question
Power factor correction in circuits having lagging power factors can be achieved by connecting:
• resistors in series with the load

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