Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Current Electricity question

2024 · 8 Apr · Shift 1 · Q87
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Physics
  4. /Current Electricity
  5. /2024 · 8 Apr · Shift 1 · Q87

Current Electricity question

2024 · 8 Apr · Shift 1 · Q87

JEE MainPhysicsCurrent ElectricityNumerical+4 / −1
Resistance of a wire at 0∘C,100∘C0^{\circ} \mathrm{C}, 100^{\circ} \mathrm{C}0∘C,100∘C and t∘Ct^{\circ} \mathrm{C}t∘C is found to be 10Ω,10.2Ω10 \Omega, 10.2 \Omega10Ω,10.2Ω and 10.95Ω10.95 \Omega10.95Ω respectively. The temperature ttt in Kelvin scale is ‾\underline{\hspace{2cm}}​.
Numerical answer
View written solutionFree

Correct answer: 748

  1. Use the linear temperature dependence of resistance

For a metallic wire, resistance varies as

Rt=R0(1+αt)R_t = R_0(1+\alpha t)Rt​=R0​(1+αt)

where:

  • R0R_0R0​ is resistance at 0∘C0^\circ\text{C}0∘C
  • α\alphaα is temperature coefficient at 0∘C0^\circ\text{C}0∘C
  • ttt is in ∘C^\circ\text{C}∘C

Given:

R0=10 ΩR_0 = 10\,\OmegaR0​=10Ω R100=10.2 ΩR_{100} = 10.2\,\OmegaR100​=10.2Ω Rt=10.95 ΩR_t = 10.95\,\OmegaRt​=10.95Ω


  1. Find α\alphaα using the value at 100∘C100^\circ\text{C}100∘C

Using

R100=R0(1+100α)R_{100} = R_0(1+100\alpha)R100​=R0​(1+100α)

Substitute values:

10.2=10(1+100α)10.2 = 10(1+100\alpha)10.2=10(1+100α)

Divide by 10:

1.02=1+100α1.02 = 1+100\alpha1.02=1+100α

So,

100α=0.02100\alpha = 0.02100α=0.02 α=0.0002=2×10−4 ∘C−1\alpha = 0.0002 = 2\times 10^{-4}\, ^\circ\text{C}^{-1}α=0.0002=2×10−4∘C−1


  1. Use resistance at t∘Ct^\circ\text{C}t∘C to find ttt

Rt=R0(1+αt)R_t = R_0(1+\alpha t)Rt​=R0​(1+αt)

So,

10.95=10(1+0.0002t)10.95 = 10(1+0.0002t)10.95=10(1+0.0002t)

Divide by 10:

1.095=1+0.0002t1.095 = 1+0.0002t1.095=1+0.0002t

Hence,

0.0002t=0.0950.0002t = 0.0950.0002t=0.095

t=0.0950.0002=475∘Ct = \frac{0.095}{0.0002} = 475^\circ\text{C}t=0.00020.095​=475∘C


  1. Convert to Kelvin

T=475+273=748 KT = 475 + 273 = 748\,\text{K}T=475+273=748K


  1. Final Answer

The temperature in Kelvin scale is

748\boxed{748}748​

PreviousNext

More from Current Electricity

  • Water boils in an electric kettle in 20 minutes after being switched on. Using the same main supply, the length of the heating element should be ​ to ​ times of its initial length if the…2024 · MCQ
  • A heater is designed to operate with a power of 1000 W in a 100 V line. It is connected in combination with a resistance of 10Ω and a resistance R, to a 100 V mains as shown in figure. For the… Includes diagram2024 · Numerical
  • A galvanometer has a coil of resistance 200Ω with a full scale deflection at 20μA. The value of resistance to be added to use it as an ammeter of range (0−20)mA is :2024 · MCQ
  • The equivalent resistance between A and B is : Includes diagram2024 · MCQ
  • The current flowing through the 1Ω resistor is 10n​ A. The value of n is ​. Includes diagram2024 · Numerical
  • The effective resistance between A and B, if resistance of each resistor is R, will be : Includes diagram2024 · MCQ
  • To determine the resistance (R) of a wire, a circuit is designed below. The V-I characteristic curve for this circuit is plotted for the voltmeter and the ammeter readings as shown in figure. The value of R is ​… Includes diagram2024 · Numerical
  • At room temperature (27∘C), the resistance of a heating element is 50Ω. The temperature coefficient of the material is 2.4×10−4∘C−1. The temperature of the element, when its…2024 · Numerical