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Test: Resistivity Temperature Coefficient of Resistance - Electrical Engineering (EE) MCQ


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20 Questions MCQ Test - Test: Resistivity Temperature Coefficient of Resistance

Test: Resistivity Temperature Coefficient of Resistance for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Test: Resistivity Temperature Coefficient of Resistance questions and answers have been prepared according to the Electrical Engineering (EE) exam syllabus.The Test: Resistivity Temperature Coefficient of Resistance MCQs are made for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Resistivity Temperature Coefficient of Resistance below.
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Test: Resistivity Temperature Coefficient of Resistance - Question 1

Materials which allow the passage of electric current are known as______

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 1

Conductors are materials(mostly metals), which freely allow the passage of electrons through it. If electrons can flow freely through a material, it implies that even current can flow freely through that material since current is the rate of flow of electrons.

Test: Resistivity Temperature Coefficient of Resistance - Question 2

A wire of length 2m and another wire of length 5m are made up of the same material and have the same area of cross section, which wire has higher resistance?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 2

Resistance is directly proportional to the length of the wire, hence as the length of the wire increases, resistance increases.

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Test: Resistivity Temperature Coefficient of Resistance - Question 3

A wire having an area of cross section = 10sqm and another wire having an area of cross section= 15sqm, have the same length and are made up of the same material. Which wire has more resistance?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 3

Resistance is inversely proportional to area of cross section. As area of cross section increases, resistance decreases. Hence the 10sqm wire has higher resistance than the 15sqm wire.

Test: Resistivity Temperature Coefficient of Resistance - Question 4

Which of the following statements are true with regard to resistance?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 4

The expression for resistance is: Resistance=Resistivity*length of wire/ area of cross section of wire. Hence resistance is directly proportional to length.

Test: Resistivity Temperature Coefficient of Resistance - Question 5

A wire has the same resistance as the one given in the figure. Calculate its resistivity if the length of the wire is 10m and its area of cross section is 2m.

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 5

From the given circuit, R=V/I= 200/5 =40ohm.
Resistivity= Resistance*Area of cross section/ Length of the wire.
Resistivity= 40*2/10= 8 ohm-metre.

Test: Resistivity Temperature Coefficient of Resistance - Question 6

Which, among the following is a unit for resistivity?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 6

Resistivity= RA/l= ohm*metre2/metre. Hence the unit of resistivity is ohm- metre.

Test: Resistivity Temperature Coefficient of Resistance - Question 7

What is the resistivity of Copper?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 7

Resistivity is a material property. Different materials have different resistivity’s. Resistivity depends on the material of the wire, hence the resistivity of copper is 1.59*10-8ohm-metre.

Test: Resistivity Temperature Coefficient of Resistance - Question 8

Calculate the ratio of the resistivity of 2 wires having the same length and same resistance with area of cross section 2m2 and 5m2 respectively.

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 8

Resistivity of first wire= RA1/l= 2R/l.
Resistivity of second wire= RA2/l = 5R/l.
Ratio of the first resistance to the second= (2A/l)/(5A/l)= 2/5.

Test: Resistivity Temperature Coefficient of Resistance - Question 9

Which of the following statements are true with regard to resistivity?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 9

Resistance is a temperature dependent element. As the temperature increases, resistance also increases, hence resistance depends on temperature.

Test: Resistivity Temperature Coefficient of Resistance - Question 10

The reciprocal of resistivity is________

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 10

The expression for resistivity is= RA/l. The expression for conductivity= Cl/A; C=1/R => Conductivity= l/(AR) = 1/resistivity. Hence, conductivity is the reciprocal of resistivity.

Test: Resistivity Temperature Coefficient of Resistance - Question 11

The resistance of pure metals ___________

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 11

In a conductor, the valence band and conduction band overlap each other, there is an excess of electrons in the conduction band. When the temperature increases, there is an overcrowding of electrons in the conduction band hence reducing the mobility and hence resistance increases.

Test: Resistivity Temperature Coefficient of Resistance - Question 12

The resistance of insulators __________

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 12

In case of an insulator, the energy gap between the conduction band and the valence band is very large. When the temperature is increased, the electrons move from the conduction band to the valence band and hence it starts conducting. When conductance increases, resistance decreases, since C=1/R. Thus, when temperature increases, resistance decreases in insulators.

Test: Resistivity Temperature Coefficient of Resistance - Question 13

Which of the following statements are true about metals?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 13

The resistance of metals increases with an increase in temperature thus, it has a positive temperature coefficient.

Test: Resistivity Temperature Coefficient of Resistance - Question 14

Which of the following statements are true about insulators?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 14

Insulators have a negative temperature coefficient because as temperature increases, the resistance of insulators decreases.

Test: Resistivity Temperature Coefficient of Resistance - Question 15

What is the unit of temperature coefficient?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 15

: R=Reff[1+temp. coeff(T-Teff)].
From the given expression: (R/Reff-1)/(T-Teff)= temp. coeff. Hence, the unit is the reciprocal of that of temperature= centigrade-1.

Test: Resistivity Temperature Coefficient of Resistance - Question 16

 A copper coil has a resistance of 200 ohm when its mean temperature is 0 degree centigrade. Calculate the resistance of the coil when its mean temperature is 80 degree centigrade.

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 16

The temperature coefficient of copper is 0.00428 centigrade-1
R1=R0(1+temp. coeff.*T1)= 200(1+0.00428*80)= 268.5 ohm.

Test: Resistivity Temperature Coefficient of Resistance - Question 17

The temperature of a coil cannot be measured by which of the following methods?

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 17

Caloriemeter measures the amount of heat and not the temperature of coil coefficient. Temperature of a coil is mainly measured by thermometer.

Test: Resistivity Temperature Coefficient of Resistance - Question 18

The rise or fall in resistance with the rise in temperature depends on________

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 18

The rise or fall in resistance with rise in temperature depends upon the property of the material. Hence it rises with temperature in metals and falls with temperature in insulators and semi-conductors.

Test: Resistivity Temperature Coefficient of Resistance - Question 19

If the temperature is increased in semi-conductors such that the resistance incessantly falls, it is termed as_______

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 19

When the temperature keeps increasing, the resistance keeps falling continuously and hence the current to increase. This causes the heat in the semi-conductor to rise. This causes the temperature to increase further and the resistance to further decrease. This process continues and until there is sufficient heat to destroy the structure of the semi-conductor completely. This is known as thermal runway.

Test: Resistivity Temperature Coefficient of Resistance - Question 20

Materials having resistance almost equal to zero is_______

Detailed Solution for Test: Resistivity Temperature Coefficient of Resistance - Question 20

When the temperature of a material falls to absolute zero, the resistance falls to zero and hence there are no I2R losses. Since resistance is zero, conductance is almost infinity and hence these materials are known as superconductors.

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