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At room temperature 27° C, the resistance of a heating element is 100 Ω. What is the temperature of the element if the resistance is found to be 117 Ω, given that the temperature coefficient of the material of resistance is 1.70×10-4 C-1.

Important Questions on Current Electricity

EASY

I and V are respectively the current and voltage in a metal wire of resistance R. The I-V graph for the two different temperatures T1 and T2 are given, then

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EASY
The resistance of a wire at 20 °C is 20 Ω and 500 °C is 60 Ω. At which temperature, its resistance will be 25 Ω ?
EASY
A piece of copper and another of germanium are cooled from room temperature to 77° K. The resistance of
MEDIUM
The resistance of the platinum wire of a platinum resistance thermometer at the ice point is 5 Ω and at steam point is 5.23 Ω. When the thermometer is inserted in a hot bath, the resistance of the platinum wire will be 5.795 Ω. Calculate the temperature of the bath.
EASY
The conductivity of semiconductor increases with increase in temperature because
HARD
The resistance of a conductor at 15°C is 16 Ω and at 100°C is 20 Ω. What will be the temperature coefficient of resistance of the conductor?
MEDIUM
The temperature co-efficient of resistance of a wire is 0.00125/°C. Its resistance is Ω at 300 K. At what temperature, its resistance will be Ω?
EASY
Copper and Silicon are cooled from 300 K to 60 K. The specific resistance
MEDIUM
In a platinum resistance thermometer, the resistances of the wire at ice point and steam point are of 4Ω and 4.25Ω respectively. When the thermometer is kept in a hot water bath, whose temperature is not known, the resistance of the wire is found to be 4.5Ω. The temperature of the hot water bath is
MEDIUM
Which of the following graph represents the variation of resistivity ρ with temperature T for copper?
MEDIUM
What will be the resistance of a wire at 0 degree celsius, if its resistance is 5ohm at 50 degree celsius and 6ohm at 100 degree celsius?
EASY
The temperature dependence of resistance of Cu and undoped Si in the temperature range 300-400 K is best described by
MEDIUM
The temperature  T dependence of resistivity ρ of a semiconductor is represented by
EASY

When the temperature of a conductor increases, the ratio of conductivity and resistivity _____

EASY
Constantan wire is used in making standard resistances because its
EASY

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Alloys such as constantan and manganin are used in making standard resistance coils.

Reason R: Constantan and manganin have very small value of temperature coefficient of resistance.

In the light of the above statements, choose the correct answer from the options given below.

EASY
Resistance of the wire is measured as 2 Ω and 3 Ω at 10°C and 30°C respectively. Temperature coefficient of resistance of the material of the wire is
EASY
The solids which have the negative temperature coefficient of resistance are:
MEDIUM

In an experiment, the resistance of a material is plotted as a function of temperature (in some range). As shown in the figure, it is a straight line.

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One may conclude that

MEDIUM
A heating element has a resistance of 100 Ω at room temperature. When it is connected to a supply of 220 V, a steady current of 2 A passes in it and temperature is 500 oC more than the room temperature. The temperature coefficient of resistance of the heating element is