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WorksheetsEMS2
Total questions: 103
Worksheet time: 52mins
Name
Class
Date
1.
The ratio of intensity of magnetisation to magnetising force is called:
a)
Susceptibility
b)
Permeability
c)
magnetic potential
d)
None of the above
2.
Which from below is that property which opposes the production of magnetic flux in it:
a)
Magnetic reluctance
b)
Remanance
c)
Retentivity
d)
Susceptibility
3.
The magnetic force demand is :
a)
Higher for hard ferro magnets
b)
Higher for hard ferrites
c)
Remains the same for two
d)
None of the above
4.
Small magnets are made by:
a)
Special casting techniques
b)
powder metallurgical technique
c)
heat treatment
d)
none of the above
5.
Ferrites are:
a)
Ferromagnetic material
b)
Ferrimagnetic material
c)
Anti ferromagnetic material
d)
None of the above
6.
Which of the followeing materiasls have maximum magnetic permeability:
a)
Pure iron
b)
4% silicon steel
c)
Grain oriented silicon-iron
d)
None of the above
7.
Curie point temperature:
a)
remains constant for all materials
b)
differs from material to material
c)
both of the above
d)
None of the above
8.
For ferromagnetic materials, the susceptibility:
a)
is constant
b)
is not constant
c)
is zero
d)
none of the above
9.
Curie temperature is the temperature above which a ferro-magnetic material becomes:
a)
Paramagnetic
b)
dimagnetic
c)
either of the above
d)
none of the above
10.
The Relative permeability of mild steel (iron) iron is around:
a)
500
b)
800
c)
1200
d)
2000
11.
Which material has best spontaneous magnetisation characteristic from below mentioned list?
a)
Ferro-magnetic
b)
Paramagnetic
c)
Diamagnetic
d)
all of the above
12.
Practically, all Organic substances are:
a)
Ferro-magnetic
b)
Paramagnetic
c)
Diamagnetic
d)
all of the above
13.
In Carbon steel, if the percentge of carbon is increased, it has which of following effects?
a)
resistivity is increased
b)
saturation temperature is lowered
c)
permeability is decresed
d)
all of the above
14.
High frequency transformer cores are generally made from:
a)
ferrites
b)
non-ferrites
c)
none of the above
d)
both of the above
15.
The relative magnetism under a given field -----, as temperature approaches the Curie point:
a)
decreases
b)
increases
c)
remains constant
d)
None of the above
16.
The Eddy current prtoduce a magnetic field of their own which --------- the main field:
a)
assist
b)
opposes
c)
does not effect
d)
none of the above
17.
The change in dimensions during the process of magnetisation is called:
a)
Magnetostriction
b)
Hall's effect
c)
Skin effect
d)
none of the above
18.
Which of the following factors cause magnetic ageing? :
a)
presense of strong external field
b)
presense of strong external field
c)
Temperature condition
d)
all of the above
19.
Which of the following materials can be used in cable shields:
a)
Copper
b)
Aluminium
c)
Cast iron
d)
Lead
20.
Variable resistors are:
a)
Carbon resistors
b)
thin film resistors
c)
cheap and easy to machine
d)
wire wound resistors
21.
we have two copper wires of 14 gauge and 20 gauge. Which of the following will be lower for 14 gauge:
a)
weight
b)
resistance
c)
cost
d)
strength
22.
The material with lowest resistivity is:
a)
Constantan
b)
German silver
c)
manganin
d)
nichrome
23.
The material with highest resistivity is:
a)
Constantan
b)
German silver
c)
manganin
d)
nichrome
24.
The heating elements of electric irons are made of
a)
copper
b)
nichrome
c)
constantan
d)
aluminium
25.
In conductors, conduction of electricity takes place due to movement of:
a)
electrons only
b)
positive ions only
c)
positive and negative ions
d)
None of the above
26.
Copper is completely miscible with
a)
nickel
b)
gold
c)
hydrogen
d)
lead
27.
A Platinum wire senses temperature because of its
a)
high resistivity
b)
high coefficient of resistance
c)
high melting point
d)
non-corroding texture
28.
On which of the following factors does the resistivity of a material depend:
a)
Resistance of the Conductor
b)
Area of the conductor section
c)
Length of the Conductor
d)
All of the above
29.
The metal having the lowest temperature coefficient of resistance from given list is:
a)
Gold
b)
Copper
c)
Aluminium
d)
Kanthal
30.
Commonly used Conducting materials are
a)
Copper
b)
Aluminium
c)
Both Copper and Aluminium
d)
Copper and Silver
31.
Which of the following materials is preferred for transmitting electrical energy over a long distance:
a)
Copper
b)
Aluminium
c)
Steel reinforced Copper
d)
Steel reinforced Aluminium
32.
High resistivity materials are used in:
a)
precision instruments
b)
heating elements
c)
incandescent lamps
d)
all of the above
33.
Mercury as an electric contact material is:
a)
a liquid
b)
a metal
c)
a metal liquid
d)
a gas
34.
The coils of DC Motor starter are wound with wire of :
a)
Copper
b)
Kanthal
c)
Manganin
d)
nichrome
35.
By increasing impurity content in the metal alloy, the residual resistivity always:
a)
decreases
b)
increases
c)
remains constant
d)
becomes temperature independent
36.
Constantan contains:
a)
Silver and Tin
b)
Copper and Tungsten
c)
Tungsten and silver
d)
Copper and Nickel
37.
Which of the following is the Poorest condutor of electricity:
a)
Carbon
b)
Steel
c)
Silver
d)
Aluminium
38.
In thermocouples which of the following pair is commonly used:
a)
Copper- Constantan
b)
Aluminium-Tin
c)
Silver-German Silver
d)
Iron-Steel
39.
Solder is an alloy of:
a)
Copper and Aluminium
b)
Tin and Lead
c)
Nickel, Copper and Zinc
d)
Silver, Copper and Lead
40.
Which material is the most commonly used for making magnetic recording tape:
a)
Silver nitrate
b)
Ferric Oxide
c)
Small particles of Iron
d)
Silicon-Iron
41.
A good electric contact material should have all of the following properties except:
a)
high resistivity
b)
High resisatance to corrosion
c)
good thermal conductivity
d)
high melting point
42.
Carbon resistors contain:
a)
Carbon Crystals
b)
Solid Carbon Granules
c)
Finely divided carbon black
d)
None of the above
43.
Which of the following material is not a Semiconductor:
a)
Silica
b)
Germanium
c)
Selenium
d)
Gallium
44.
Platinum is used in:
a)
Electrical Contacts
b)
Thermocouples
c)
Heating elements in high temperature furnace
d)
all of the above
45.
Due to which of the following reasons, Copper and Aluminium are not used for heating elements:
a)
Both have great tendency for oxidation
b)
both have low melting point
c)
very large length of wires will be required
d)
all of the above
46.
Copper, even though costly, find uses in the windings of electrical machines, because:
a)
Copper points offer low contact resistance
b)
Copper can be easily soldered and welded
c)
Copper windings are less bulky and the machine becomes compact
d)
all of the above
47.
Substances whose specific resistances decreases abruptly at low temperature are called:
a)
Insulators
b)
Conductors
c)
Semiconductors
d)
Superconductors
48.
From below given facts, which one is most suitable for replacing copper with aluminium?
a)
Aluminium is more ductile and malleable than Copper
b)
Aluminium is available in plenty, cheaper and lighter than Copper
c)
Aluminium has lower resistivity than that of Copper
d)
Aluminium has less temperature coefficient than Copper
49.
If a resistance of a conductor does not vary in accordance with OHM's law, it is known as:
a)
Non-linear conductor
b)
Bad conductor
c)
non-conductor
d)
all of the above
50.
Reluctivity is analogus to:
a)
Permeability
b)
Conductivity
c)
Resistivity
d)
Retentivity
51.
Hysteresis loss depends on :
a)
Frequency
b)
Magnetic field intensity
c)
Volume of the material
d)
all of the above
52.
Eddy current in a core will be reduced considerably by:
a)
reducing flux density
b)
laminating core
c)
reducing core volume
d)
increasing the number of turns
53.
Insulators have:
a)
Large energy gap
b)
an empty conduction band
c)
a full valence band
d)
None of the above
54.
Resistivity of electrical conductors is most effected by:
a)
Pressure
b)
Temperature
c)
Composition
d)
Ageing
55.
Application of paper in insulating material is restricted to temperature upto:
a)
50 degree centigrade
b)
70 degree centigrade
c)
100 degree centigrade
d)
180 degree centigrade
56.
Spark plug makes use of insulation from which of the following given materials?
a)
Porcelin
b)
Slate
c)
Asbestos
d)
Glass
57.
Effect of moisture on the insulating materials is to :
a)
decrease dielectric conatant
b)
decrease dielectric strength
c)
decrease insulation resistance
d)
all of the above
58.
Insulators are the materials in which valence electrons are bounded:
a)
loosely to their parent atoms
b)
moderately to their parent atoms
c)
very tightly to their parent atoms
d)
None of the above
59.
A good insulating material should possess which of the following characteristic:
a)
High insulation resistance
b)
High dielectric strength
c)
Least thermal expansion
d)
all of the above
60.
The dielectric strength of mica varies from :
a)
10 to 20 KV/mm thickness
b)
20 to 30 KV/mm thickness
c)
30 to 40 KV/mm thickness
d)
40 to 150 KV/mm thickness
61.
Porcelain insulators are employed for insulating terminals of:
a)
Low voltage machine
b)
Medium voltage machine
c)
High voltage machine
d)
all of the above
62.
The dielectric strength of paper is:
a)
2 to 4 KV/mm thickness
b)
4 to 10 KV/mm thickness
c)
10 to 15 KV/mm thickness
d)
15 to 20 KV/mm thickness
63.
Which one of the following given insulating materials, is in most common use for Overhead Power lines?
a)
Porcelain
b)
Toughened glass
c)
Both the above
d)
None of the above
64.
The function of insulating liquid is:
a)
To provide electrical insulation
b)
to provide heat transfer
c)
both the above
d)
None of the above
65.
Which of the following tests is carried out on Transformer oil:
a)
Moisture test
b)
Acidity test
c)
Dielectric strength test
d)
all of the above
66.
Presense of even a trace of water in transformer oil -------- its insulation strength considerably:
a)
Reduces
b)
Increases
c)
does not effect
d)
None of the above
67.
Insulating gases entail which of the following major problems:
a)
Temperature instability
b)
Abnormalities in dielectric behaviour at high pressures
c)
Fire hazards
d)
all of the above
68.
Insulation resistance --------- with increase in temperature:
a)
Decreases
b)
Increases
c)
Remains uneffected
d)
None of the above
69.
Dielectrics have:
a)
A few free electrons
b)
Many free electrons
c)
No freee electrons
d)
None of the above
70.
Dielectric materials are essentially :
a)
Insulating materials
b)
Conducting materials
c)
Semiconducting materials
d)
Ferro-electric materials
71.
Dielectric strength is expressed in:
a)
Kv/mm
b)
Kv/mm square
c)
Kv/mm cube
d)
None of the above
72.
The dielectric strength of transformer oil should be:
a)
100 V
b)
5 KV
c)
30 KV
d)
132 KV
73.
Which of the following kind of break-downs is possible in solid dielectrics ?
a)
Electrothermal breakdown
b)
Purely electrical breakdown
c)
Electrochemical breakdown
d)
all of the above
74.
Loss in dielectric may occur due to:
a)
Polarisation
b)
Conductivity
c)
Ionisation
d)
all of the above
75.
Electrolytic capacitors are :
a)
Fixed value capacitors
b)
Variable value capacitors
c)
both of the above
d)
None of the above
76.
Piezo-electric effect converts:
a)
Electrical energy to mechanical enegy
b)
Mechanical energy to Electrical enegy
c)
both of the above
d)
None of the above
77.
Capacitors that use vacuum, air or other gases as dielectric have:
a)
low energy loss
b)
high energy loss
c)
Zero energy loss
d)
all of the above
78.
Photo diode is :
a)
Forward biased junction diode
b)
Reverse biased junction diode
c)
none of the above
d)
all of the above
79.
All transducers act as
a)
Sensors only
b)
It senses signal and transforms energy in other form
c)
none of the above
d)
both of the above
80.
LED is a PN junction which emitts light when it is biased :
a)
Forward
b)
Reverse
c)
none of the above
d)
all of the above
81.
Pyroelectricity is the ability of certain materials to generate a temporary voltage when they are:
a)
Heated
b)
Cooled
c)
both of the above
d)
none of the above
82.
10 nm = _____ m
a)
10-8
b)
10-7
c)
10-9
d)
10-10
83.
The size of nanoparticles is between _____ nm.
a)
100 to 1000
b)
0.1 to 10
c)
1 to 100
d)
0.01 to 1
84.
1 micrometer (micron) = ______ m.
a)
10-9
b)
10-8
c)
10-7
d)
10-6
85.
The full form of STM is...
a)
Scanning Tunneling Microscope
b)
Scientific Technical Microscope
c)
Systematic Technical Microscope
d)
Super Tensile Microscope
86.
The applications of nanotechnologies are expected to bring everyday benefits for
consumers through:
a)
new products
b)
novel health applications
c)
reduced
environmental impacts
d)
all of the above
87.
The two important properties of nanosubstances are...
a)
pressure and friction
b)
sticking and friction
c)
sticking and temperature
d)
temperature and friction
88.
The electrical conductivity of a nanotube is ____ times that of copper.
a)
10
b)
100
c)
1000
d)
1/10
89.
What is the general name for the class of structures made of rolled up carbon lattices?
a)
Nanorods
b)
Nanotubes
c)
Nanosheets
d)
Fullerrods
90.
What are the advantages of nano composite packages?
a)
Light and biodegradable
b)
Enhanced thermal stability, conductivity and mechanical strength
c)
Gas barrier properties
d)
All of the mentioned
91.
Due to _________ tensile strength some of the nano materials are used in air crafts.
a)
High
b)
Low
c)
Moderate
d)
No
92.
Which of the following is the application of nanotechnology to food science and technology?
a)
Agriculture
b)
Food and biosecurity
c)
Product development
d)
all of the above
93.
Before selecting an insulation system for a particular application, we consider:
a)
Mechanical property
b)
Environmental including chemical property
c)
Thermal property
d)
all of the above
94.
Thermal properties of an insulation system include:
a)
working temperature
b)
time of exposure
c)
Both the above
d)
none of the above
95.
Environmental properties of an insulation system include:
a)
effect of air
b)
effect of light
c)
alkali and acid fumes
d)
all of the above
96.
Dielectric gases are used as an:
a)
insulant
b)
heat transfer medium
c)
Both the above
d)
none of the above
97.
Hydrocarbon dielectric gases are:
a)
Methane
b)
Ethane
c)
Propane
d)
all of the above
98.
Sulphur hexafluoride , as a dielectric gas, is used for:
a)
High voltage application
b)
Gas lasers
c)
Foundary practice
d)
all of the above
99.
An ideal insulating liquid should contain:
a)
High electric strength and non-flammable
b)
high specific heat and thermal conductivity
c)
Excellent chemical stability and good arc quenching property
d)
all of the above
100.
Insulating materials used in power and distribution transformers must possess:
a)
Good electrical property to withstand impulse over voltages
b)
Good mechanical property to withstand during overload, short circuit
c)
good thermal stability
d)
all of the above
101.
The dielectric used for cables must have:
a)
low dischsrge current
b)
Chemically stable
c)
both of the above
d)
none of the above
102.
Hydrocarbon liquid dielectrics have:
a)
low permittivity
b)
low dielectric factor
c)
high electric strength
d)
all of the above
103.
Gauss meter is an instrument used to measure :
a)
Flux density
b)
Intensity of magnetic field
c)
Both the above
d)
none of the above
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