A conductive wire has a resistance of 10 ohm at 0 ° C and α is 1 273 ° C - 1 , then determine its resistance at 273 ° C .

In such a problem, term α Δ T will have a larger value, so it could not be used directly in R 2 = R 1 ( 1 + α Δ T ) . We need to go for basics. As we know that, d R d T = α R ∫ R 1 R 2 d R R = ∫ T 1 T 2 α d T ln R 2 R 1 = α T 2 - T 1 R 2 = R 1 e α T 2 - T 1 Here, R 1 = 10 Ω at T 1 = 0 ° C and resistance R 2 at T 2 = 273 ° C R 2 = 10 e 1 273 273 - 0 R 2 = 10 e = 27 . 18 Ω .

MEDIUM

JEE Advanced

IMPORTANT

Earn 100

It is desired to make a $20 Ω$ coil of wire, which has a zero thermal coefficient of resistance. To do this, a carbon resistor of resistance $R_{1}$ is placed in series with an iron resistor of resistance $R_{2}$ . The proportions of iron and carbon are so chosen that $R_{1} + R_{2} = 20 Ω$ for all temperatures near $20 ° C$ . Find the values of $R_{1}$ and $R_{2}$ ? ( $α_{carbon} = - 0.5 \times 10^{- 3 \circ} C^{- 1}, α_{iron} = 5 \times 10^{- 3 \circ} C^{- 1}$ ).

Important Questions on Electric Current and Circuits

MEDIUM

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 10

A resistance thermometer measures temperature with the increase in resistance of a wire of high temperature. If the wire is platinum and has a resistance of

10 Ω

20 ° C

and resistance of

35 Ω

in a hot furnace, what is the temperature of the furnace?

(α_{platinum} = 0.0036 ° C^{- 1})

MEDIUM

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 11

A conductive wire has a resistance of

10 ohm

0 ° C

and

α

\frac{1}{273} ° C^{- 1}

, then determine its resistance at

273 ° C

MEDIUM

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 12

What is the drift speed of the conduction electrons in a copper wire with radius

r = 900 μ m

when it has a uniform current

i = 17 mA

? Assume that each copper atom contributes one conduction electron to the current and the current density is uniform across the wire's cross-section. (The density of copper is

ρ = 9 \times 10^{3} kg m^{- 3}

and atomic mass of copper is

M = 63.5 amu

)

EASY

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 13

(a) At what temperature would the resistance of a copper conductor be double its value of $0 ° C ?$

(b) Does this same temperature hold for all copper conductors, regardless of shape and size? $[α_{C} = 4.0 \times 10^{- 3} {° C}^{- 1}]$

MEDIUM

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 14

A potential difference is applied across the filament of a bulb at

t = 0,

and it is maintained at a constant value while the filament gets heated to its equilibrium temperature. We find that the final current in the filament is one-sixth of the current drawn at

t = 0 .

If the temperature of the filament at

t = 0

20 ° C

and the temperature coefficient of resistivity at

20 ° C

0.0043 {{}^{\circ}C}^{- 1},

find the final temperature of the filament.

EASY

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 1

A battery of emf

2 V

and internal resistance

0.1 Ω

is charged with a current of

5 A

. In what direction will the current flow inside the battery? What is the potential difference between the two terminals of the battery?

EASY

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 2

The potential difference across the terminals of a cell was measured (in

volts

) against different currents (in

ampere

) flowing through the cell. A graph was drawn, which was a straight line

A B C

. Using the data given in the graph (see figure), determine
Question Image

(a)

the emf, and

(b)

the internal resistance of the cell.

EASY

JEE Advanced

IMPORTANT

PHYSICS for Joint Entrance Examination JEE (Advanced) Electrostatics and Current Electricity>Chapter 5 - Electric Current and Circuits>Concept Application Exercise>Q 3

Determine the voltage drop across the resistor $R_{1}$ in the circuit given below with $E_{1} = 65 V$ , $R_{1} = 50 Ω$ , $R_{2} = 100 Ω$ , $R_{3} = 100 Ω$ and $R_{4} = 300 Ω$ .
Question Image

Important Questions on Electric Current and Circuits

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