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WorksheetsPrinciples of Electrical Science
Total questions: 39
Worksheet time: 25mins
From a 50 metre cable drum, you have installed 13.6 metres of cable. What percentage of cable has been used?
3.8%
72.8%
27.2%
65%
An insulation resistance tester is used to record the following values: 55MΩ, 72MΩ, 55MΩ, 18.5Ω, 10 MΩ and 89MΩ. What is the mean of these values?
49.9MΩ
89MΩ
55MΩ
18.5MΩ
The SI unit for resistivity is?
Ohm
Ωm
R
Ω
Potential Difference is measured in?
Amps
Volts
Newton's
Joule's
In the SI system, time is measured in?
Hours
Minutes
Seconds
Kelvin's
Which instrument would be used to measure the resistance of a circuit?
Ohm meter
Conductance meter
Continuity meter
Amp meter
The SI unit for Capacitance is the?
Volt
Henry
Hertz
Farad
Lifting a load an electric motor uses 180,000 Joules of energy in 1 ½ minutes. What is the power rating of the motor?
500 W
1 kW
1.5 kW
2 kW
Crowbars are an example of what type of lever?
Class 1
Class 2
Class 3
Class 4
Force on a load is considered to be a combination of:
mass and gravity
time and acceleration
weight and energy
energy and work done
An electric motor has a 1.8 kW input and an efficiency of 88%. What is the motor's output?
1.12 kW
160 W
1.6 kW
160 kW
A four pulley system is required to lift a load force of 20000 Newton's. What is the effort force required to lift this load?
5000 N
800000 N
5000 kg
10000 N
A set of gears has a ratio of 16:1. The smaller cogwheel has 9 teeth. How many teeth does the larger cogwheel have?
14
41
82
144
Current is described as:
the pressure to move the charge within a circuit.
the movement of electrons within a closed circuit.
the movement of protons within a conductor.
the standing force of the neutrons within an open circuit.
Porcelain is best described as?
A good conductor of electricity
A semi-conductor of electricity
An unstable conductor of electricity
A good insulator of electricity
A 2.5mm2 copper conductor has a resistance of 1.5 Ohms. If the conductor's length is doubled what would the resulting resistance be?
6 Ohms
1.5 Ohms
3 Ohms
0.3 Ohms
A copper conductor has a resistance of 0.62 Ohms and is 36 meters long. What size is the conductor? Take the resistivity of copper to be 0.0172µΩm.
1mm2
1.5mm2
2.5mm2
4mm2
Two 4mm2 copper conductors are connected in parallel. Each conductor has a resistance of 0.5 Ohms. What is the combined resistance of the two conductors?
0.5 Ohms
0.25 Ohms
1 Ohm
0.75 Ohms
Four resistors each with an equal value of 6 Ohms are wired in parallel. What is the combined total resistance of the resistors?
24 Ohms
3 Ohms
1.5 Ohms
0.75 Ohms
A 5 Ohm resistor and a 7 Ohm resistor are wired in series and connected to a 25 volt supply. What is the power dissipated in the 7 Ohm resistor?
52 Watts
57 Watts
89 Watts
30 Watts
A copper conductor is forty meters long and has a c.s.a of 6mm2. If the conductor material was changed to aluminium the resulting resistance would be:
the same
lower
higher
unstable
Which statement is correct with regards to what makes a good insulator?
The electrons are tightly bound to the nucleus.
The electrons are loosely bound to the nucleus.
The protons are tightly bound to the nucleus.
The protons are loosely bound to the nucleus.
Which of the following materials is a good conductor of electricity?
Air
Tungsten
Glass
Sand
Which effect would make a Fuse blow?
Chemical
Magnetic
Thermal
Solar
What is the total combined resistance of the resistors show in the figure below?
35 Ohms
11.6 Ohms
2.9 Ohms
4.5 Ohms
What is the missing voltage value in the figure below?
25 Volts
12.5 Volt
50 Volts
27.5 Volts
A 16 Amp motor is connected to a cable with a very high resistance. Which of the following issues would occur?
The motor will pull more current than it is designed to pull and damage itself.
Too much voltage will appear at the motor terminals damaging the motor.
There will be not enough voltage to operate the motor.
The motor would run in reverse.
An aluminium conductor has a resistance of 0.88 Ohm's and a c.s.a of 1.5mm2. How long is the conductor if it's resistivity is 2.84x10-8 Ωm?
46.5 m
23 m
34.5 m
62 m
Magnetic Flux Density is defined by:
the measurement of quantity of magnetic flux.
the amount of flux in a given area.
the strength of a magnetic.
the magnets north and south poles.
A electric motor has a magnetic flux density of 30 Tesla's which covers an area of 250mm2. What is the motor's magnetic flux value?
75 Wb
750 Wb
7.5mWb
7.5µWb
To induce an EMF into a conductor, what must you do?
Wrap the conductor around a magnet
Place and hold still a closed conductor within a magnetic field
Attach a magnet onto a conductor
Pass a closed conductor through a magnetic field
Identify the slip rings in the figure below.
Identify the figure below the Period?
The formula to calculate the induced EMF within a conductor is:
E=VIL
E=BIL
E=vBl
E=WbIL
How long would a conductor need to be to produce 12 Volts when passed through a 0.9 Tesla magnet at 4m/s?
33 m
3.3 m
33 cm
33 mm
Identify the device in the figure below?
Triac
Diac
Resistor
Diode
In which of the following equipment would you expect to find a light dependant resistor?
Smoke Detector
Rectifier
Solar sensor
Dimmer switch
Identify the device in the figure below?
Triac
Thermistor
Resistor
Inverter
Which device is used to change alternating current into direct current?
Inverter
Pacifier
Converter
Rectifier
