WorksheetsElectricity and Magnetism Quiz
Total questions: 47
Worksheet time: 24mins
Charge is a flow of?
electrons
neutrons
atoms
protons
The negatively charged part of an atom is called the
electron
neutron
ion
proton
Which of the following rely upon the chemical effect?
filament lamp
alternator
thermocouple
electric cell
Which of the following rely upon the heating effect?
alternator
thermocouple
motor
electroplating
When the current through a conductor increases
the resistance decreases
the temperature increases
the temperature decreases
the voltage decreases
The symbol shown below represents
battery
capacitor
inductor
resistor
The SI unit of temperature is degrees
celcius
Fahrenheit
Kelvin
rankine
The SI unit of volume is
m²
cm³
m³
m/sec
If the resistivity of copper is 0.0178μΩ/m, the resistance of 50m of 2.5mm² conductor is
0.356 Ω
0.536 Ω
0.178 Ω
0.235 Ω
3 12Ω resistors are connected in parallel to a 200V supply, calculate the total power of the circuit.
1,111W
1,000W
400W
10,000W
To measure the current through a load the meter must be connected
In series with the load
in parallel with the load
in parallel with the supply
across the load
Two resistors of 20 ohms and 40 ohms are connected in series across a 120v d.c. supply, the current flowing in the circuit will be:
0.5 A
2 A
5 A
20 A
Which of the instrument numbers would measure current (diagram missing)
1
2 and 3
1 and 3
none of them
If four resistors each of 50 Ω are connected in parallel the overall resistance is
25 Ω
100 Ω
12.5 Ω
200 Ω
When current flows in a conductor, a magnetic field is created around the conductor
only when d.c is applied
as long as the current flows
only if it is a coil
when the voltage is high enough
For the direction of current shown the north pole is
above the solenoid
at the left of the solenoid
at the right of the solenoid
below the solenoid
What value of EMF would be induced from an alternator with a conductor of 40cm rotating at a velocity of 25m/s within a magnetic flux density of 3 Tesla
30 V
300 V
3 V
33 V
Which of the following would be the approximate peak value for a supply of 150V rms
212 V
106 V
235 V
95 V
If the frequency of supply is 1.5kHz, the periodic time is
0.66ms
66ms
660s
0.00006s
According to the diagram, A represents
the peak amplitude
the peak to peak amplitude
the frequency
the time period
If an object has a mass of 50 Kg on earth, in space its mass would be
5.1 kg
50 kg
490 kg
100 kg
A load of 50Kg has a force of 25N applied. What is the acceleration of the load?
5 m/s²
0.5 m/s²
50 m/s²
2 m/s²
What is the power of a hoist required to lift an object of 20kg 20m in 30 seconds?
130.8W
13.3W
1.3kW
3.3kW
Pliers rely on which principle for their operation?
leverage
tension
torsion
friction
A motor has an input power of 50kW and an output power of 47kW. What is the efficiency of the motor?
100 %
96 %
94 %
86 %
A motor has an output power of 40kW and an efficiency of 80%. What is the input power of the motor?
32 kW
50 kW
40 kW
54 kW
Which of the following values would be the approximate value of line current for a delta connected load with a phase current of 60A?
34.7 A
60 A
130 A
104 A
Which of the below values shows the phase voltage for a star connected load
A
B
C
D
Which of the above values shows the phase current for a delta connected load
A
B
C
D
Which of the following values is the approximate neutral current for a balanced star connected load drawing 12 A per phase
12 A
0 A
20.78 A
36 A
Why is it important to balance three phase loads as evenly as possible across the three phases
A to reduce disconnection times
B to reduce the voltage
C to reduce the neutral current
D to improve the power factor
Which of the below values shows the line voltage for a delta connected load
A
B
C
D
Which of the following would not require a neutral connection?
A single phase load
B three phase unbalanced loads
C three phase balanced loads
D T.T system
Which of the following values would be the approximate value of phase voltage for a delta connected load with a line voltage of 400V
A 693.2 V
B 231.2 V
C 400 V
D 692.8 V
The power input to a machine is 90 W and the output power is 60 W the efficiency of the machine is
A 80 %
B 75 %
C 66.6 %
D 86 %
The force of gravity on earth is considered to be
A 98.1 m/s²
B 0.98 m/s²
C 981 m/s²
D 9.81 m/s²
The weight of an object is the
force acting directly below the object due to gravity
force acting on top of the object due to gravity
mass of the object divided by 9.81
the same as the mass when there is gravity
A mass of 9.5 Kg exerts a force on earth of
93.2 N
9.5 N
95 N
9.3 N
What value of EMF would be induced from an alternator with a conductor of 0.3m rotating at a velocity of 30m/s within a magnetic flux density of 2 Tesla
180 V
18 V
1800 V
1.8 V
Instrument 3 below is measuring
the voltage across the resistor
the supply current
the current through the resistor
the power through the resistor
Which direction will the conductor move if the following conditions were present?
down
left
right
up
What would be the effect on the magnetic fields for the two equal current carrying conductors shown?
the magnetic field around the two conductors would double in strength
the magnetic field around the two conductors would halve in strength
the magnetic field around the two conductors would cancel each other out
the magnetic fields will oppose each other
What would be the output voltage for a transformer with a turn ratio of 1:20 and a supply voltage of 50V?
100 V
250 V
2.5 V
1000 V
What would be the effect on the magnetic fields for the two equal current carrying conductors shown
the magnetic field around the two conductors would double in strength
the magnetic field around the two conductors would halve in strength
the magnetic field around the two conductors would cancel each other out
the magnetic fields will reverse
A wound rotor motor has windings on
the stator only
the rotor only
the rotor and stator
field and armature
What is the function of the choke in a fluorescent light fitting
improve power factor
radio suppression
limit the current through the lamp
improve the efficiency
In a three phase induction motor the stator windings
produce a rotating magnetic field
produce a pulsating magnetic field
create a leading power factor
are connected to a commutator
