Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app

NTA Abhyas 2020

Exam: NTA Abhyas
Year: 2020
Subject: Physics
Chapter: Thermal Properties of Matter

NTA Abhyas 2020 · Physics · Thermal Properties of Matter

Two electric lamps A and B radiate the same power. Their filaments...

Two electric lamps

A

and

B

radiate the same power. Their filaments have the same dimensions and have emissivities

{e}_{A}

and

{e}_{B}

respectively. Their surface temperatures are

{T}_{A}

and

{T}_{B}

. The ratio

\dfrac{{T}_{A}}{{T}_{B}}

will be equal to

Options

A ${( \dfrac{{e}_{B}}{{e}_{A}} )}^{1 / 4}$
B ${( \dfrac{{e}_{B}}{{e}_{A}} )}^{1 / 2}$
C ${( \dfrac{{e}_{A}}{{e}_{B}} )}^{1 / 2}$
D ${( \dfrac{{e}_{A}}{{e}_{B}} )}^{1 / 4}$

Correct answer

A. ${( \dfrac{{e}_{B}}{{e}_{A}} )}^{1 / 4}$

Step-by-step solution

The power radiated by a filament is

P = eA \left(\sigmaT^{4}\right) \text{ and } (where

e =

emissivity, \sigma = Stefan's constant and

T =

surface temperature)<br />Here,

eT^{4} =

constant or

{e}_{A} {T}_A^{4} = {e}_{B} {T}_B^{4}

Practice Thermal Properties of Matter on Quantrex Academy →

More from Thermal Properties of Matter

As shown in the figure, an insulated container is fitted with a thermally conducting but… JEE Advanced 2026 The heat extracted out of x gram of water initially at 50°C to cool it down to 0°C is… JEE Main 2026 The temperature of a metal strip having coefficient of linear expansion α is increased… JEE Main 2026 Which of the following best represents the temperature versus heat supplied graph for… JEE Main 2026 10 kg of ice at -10^ ∘ C is added to 100 kg of water to lower its temperature from 25 ^ ∘… JEE Main 2026 A brass wire of length 2 m and radius 1 mm at 27^ ∘ C is held taut between two rigid… JEE Main 2026 Rods x and y of equal dimensions but of different materials are joined as shown in… JEE Main 2026 An aluminium and steel rods having same lengths and cross-sections are joined to make… JEE Main 2026 Full Thermal Properties of Matter list All NTA Abhyas JEE Main PYQs