Important Basic Electrical MCQs
In this post, some of the important Basic Electrical mcqs are given. It includes reciprocal of resistivity, unit of conductivity, unit of conductance, ohm’s law, semiconductor at low temperature, resistivity of semiconductor material, temperature co-efficient of pure metal, temperature co-efficient of metal alloy, heating material, valance electrons in conductor, valance electrons in semiconductor, resistance of electrolyte, unit of temperature co-efficient of resistance and zero resistivity materials.
Basic Electrical MCQs 41 to 45
41 The reciprocal of resistivity is known as
( a )Conductance
( b )Conductivity
( c )Resistivity
( d )Permeability
Correct Answer ( b ): Conductivity
42 The unit of conductivity is
( a )Siemens / meter
( b )Siemens
( c )1 / Siemens
( d )Ohm – meter
Correct Answer ( a ): Siemens / meter
The conductance is reciprocal of resistance. R = ρL / A
G = 1/ρ ( A / L )
= σ ( A / L )
Where σ = Conductivity and G = conductance
Therefore, unit of σ = G × L / a = Siemens × Meter / Meter Square
= Siemens / Meter
43 The unit of conductance is
( a )Ohm
( b )Siemens
( c )Ohm –1
( d )Both ( b ) and ( c )
Correct Answer ( d ): Both ( b ) and ( c )
Conductance = 1/R = 1/ρ ( A / L )
The unit of conductor is ohm – 1 OR Siemens
44 Which of the following relation is true?
( a )V = IR
( b )I = VR
( c )R = VI
( d )V = I2R
Correct Answer ( a ): V = IR
45 Ohm’s law is not applicable to
( a )Non-metallic
( b )Silicon carbide
( c )Metal
( d )Both ( a ) and ( b )
Correct Answer ( d ): Both ( a ) and ( b )
Ohm’s law is not applicable for non-linear resistors or say V – I characteristics is not linear such as incandescent lamps, diodes, thermistors and varistors.
Basic Electrical MCQs 46 to 50
46 Which of the following must be constant for ohm’s law?
( a )Pressure
( b )Velocity
( c )Temperature
( d )Voltage
Correct Answer ( c ): Temperature
47 The semiconductor material at very low temperature acts as
( a )Conductor
( b )Insulator
( c )Super conductor
( d )None of the above
Correct Answer ( b ): Insulator
48 The free electrons in the insulator material are
( a )Zero
( b )One hundred
( c )1.6 x 1019
( d )One thousand
Correct Answer ( a ): Zero
The electrons in the insulating materials are tight binding to each other therefore free electrons are zero.
49 The resistivity of pure semiconductor material is in the range of
( a )1012 Ω – m
( b )10 –12 Ω – m
( c )1 Ω – m
( d )Zero
Correct Answer ( c ): 1 Ω – m
50 The temperature co – efficient of pure metal is
( a )Positive
( b )Negative
( c )Zero
( d )Any of the above
Correct Answer ( a ): Positive
Basic Electrical MCQs 51 to 55
51 The resistance of copper material becomes zero at temperature of
( a )0oC
( b )28oC
( c )– 234.5oC
( d )– 234.5oF
Correct Answer ( c ): – 234.5oC
52 The temperature coefficient of alloy material is
( a )Zero
( b )Small positive
( c )Negative
( d )Positive
Correct Answer ( b ): Small positive
53 Which of the following material is used for making heating elements?
( a )Copper
( b )Aluminum
( c )Metal alloys
( d )Nickel
Correct Answer ( c ): Metal alloys
54 The valance electrons in the conductor material are
( a )4
( b )< 4
( c )> 4
( d )Zero
Correct Answer ( b ): < 4
The valance electrons in the conductors are less than 4, semiconductor is equal to 4 and insulator greater than 4.
55 The valance electrons in the semiconductor materials are
( a )< 4
( b )4
( c )> 4
( d )Zero
Correct Answer ( b ): 4
Basic Electrical MCQs 56 to 60
56 The resistance of the electrolyte _____ with increase in the temperature.
( a )Increases
( b )Decreases
( c )Does not affect
( d )Any of the above
Correct Answer ( b ): Decreases
The electrolyte has negative temperature co-efficient therefore its resistance decreases with increase in temperature.
57 The temperature coefficient of semiconductor material is
( a )Positive
( b )Negative
( c )Zero
( d )Any of the above
Correct Answer ( b ): Negative
58 As the temperature increases, the resistance of the _____ increases irregular and small.
( a )Pure metal
( b )Alloys
( c )Insulator
( d )Semiconductor
Correct Answer ( b ): Alloys
59 The unit of temperature coefficient of resistance is
( a )Ω / m
( b )1 / oC
( c )Ω / oC
( d )Mho / oC
Correct Answer ( b ): 1 / oC
Temperature co-efficient of resistance α = ΔR / R ( ΔT )
Where ΔR = Change in resistance
ΔT = Change in temperature
Therefore α = 1 / ( ΔT ) = 1 / oC
60 Which of the following materials have zero resistivity?
( a )Conductors
( b )Semiconductors
( c )Insulators
( d )Super conductors
Correct Answer ( d ): Super conductors
The electric resistance in the super conductor material is zero therefore it does not product any heat.
More Detail About Super Conductor Materials
Basic Electrical MCQs PDF
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