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WorksheetsScience & Maths revision
Total questions: 21
Worksheet time: 42mins
Name
Class
Date
1.
The current in a coil changes from 5 amperes to 2 amperes in 50mS and induces a voltage of 30v into the coil. Calculate the value of the inductance of the coil.
a)
0.1H
b)
0.5H
c)
1.1H
d)
3H
2.
What term is used to describe the ability of a capacitor to store a charge?
a)
capacitance
b)
charge
c)
volume
d)
capacitive reactance
3.
The peak-to-peak voltage of a sinusoidal waveform is?
a)
0.5 x peak
b)
peak
c)
2 x peak
d)
4 x peak
4.
Which electronic component has the function of detecting changes in light levels?
a)
photo transistor
b)
opto coupler
c)
fibre optic cable
d)
thyristor
5.
What cable type was commonly used for underground power distribution?
a)
MIMS
b)
PILC
c)
LSF
d)
HOFR
6.
A transformer has 1000v (V pri) and 200v (V sec). If current (pri) is 5A, calculate the secondary current.
a)
5A
b)
25A
c)
1A
d)
10A
7.
What is the primary function of an isolator?
a)
to make/break current only
b)
to make/break voltage and current
c)
to act an an on-load device
d)
to act as an off-load device
8.
How is the primary earth connection made on a TT earthing system?
a)
metallic sheath of the supply cable
b)
earth rod into the ground
c)
combined earth/neutral conductor
d)
utilisation of water and gas pipes
9.
Under what fault conditions does a RCD operate?
a)
phase to earth fault
b)
phase to neutral fault
c)
open circuit fault in a phase conductor
d)
open circuit in an earth conductor
10.
What is the primary function of a fuse?
a)
to protect circuit conductors from damage
b)
to protect against electric shock
c)
to protect appliances connected in the circuit
d)
to protect against motor start-up currents
11.
A copper conductor has a ρ=17.8 nano ohms per metre and is 22 metres in length. If the cross-sectional area of the conductor is 6 sq mm, calculate the overall resistance of the conductor.
a)
45.8 ohms
b)
0.065 ohms
c)
0.45 ohms
d)
1.5 ohms
12.
A copper conductor has a ρ=17.8 nano ohms per metre and is 29 metres in length. If the overall resistance of the conductor is 0.2065 ohms, calculate the overall cross-sectional area of the conductor (in sq mm)
a)
1.0 sq mm
b)
2.5 sq mm
c)
1.5 sq mm
d)
4.0 sq mm
13.
Calculate the total resistance for the following resistor values connected in series, 2 ohms 6 ohms and 10 ohms
a)
2 ohms
b)
1 ohm
c)
18 ohms
d)
zero ohms
14.
Calculate the total resistance for the following resistor values connected in parallel, 2 ohms 6 ohms and 10 ohms
a)
0.77 ohms
b)
18 ohms
c)
1.3 ohms
d)
zero ohms
15.
Calculate the total resistance for the following resistor values connected in parallel, 10 ohms 10 ohms and 20 ohms
a)
0.25 ohms
b)
40 ohms
c)
4 ohms
d)
10 ohms
16.
Identify the conductor material from this list
a)
lead
b)
p.v.c
c)
air
d)
glass
17.
Identify the semi-conductor material from this list
a)
lead
b)
copper
c)
silicon
d)
rubber
18.
If a machine requires 12kVA of power and delivers only 9kW of useful work, calculate the overall efficiency of the machine
a)
1
b)
0.85
c)
0.75
d)
0.65
19.
Identify the 'class' of lever represented by a crow-bar
a)
class 1
b)
class 2
c)
class 3
d)
class 4
20.
A mass = 10kg is lifted 5 metres up a ladder. Calculate the force required to lift the mass
a)
490.5 N
b)
98.1 N
c)
50 N
d)
2 N
21.
A mass = 10kg is lifted 5 metres up a ladder. Calculate the power required to lift the mass in 30 seconds
a)
490.5 W
b)
16.35 W
c)
50 W
d)
2 W
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