Physics · Heat Transfer

JEE Advanced 2023 — Paper 1 — Question 31

Match the temperature of a black body given in List-I with an appropriate statement in List-II, and choose the correct option. [Given: Wien's constant as 2.9×10−3 m−K2.9 \times 10^{-3} \mathrm{~m}-\mathrm{K} and hce=1.24×10−6 V−m\frac{\mathrm{hc}}{\mathrm{e}}=1.24 \times 10^{-6} \mathrm{~V}-\mathrm{m} ]

LIST-ILIST-II
P) 2000 K1) The radiation at peak wavelength can lead to emission of photoelectrons from a metal of work function 4 eV
Q) 3000 K2) The radiation at peak wavelength is visible to human eye.
R) 5000 K3) The radiation at peak emission wavelength will result in the widest central maximum of a single slit diffraction
S) 10000 K4) The power emitted per unit area is 1/161 / 16 of that emitted by a blackbody at temperature 6000 K.
5) The radiation at peak emission wavelength can be used to
  1. Option A:

    P→3,Q→5,R→2, S→3\mathrm{P} \rightarrow 3, \mathrm{Q} \rightarrow 5, \mathrm{R} \rightarrow 2, \mathrm{~S} \rightarrow 3

  2. Option B:

    P→3,Q→2,R→4, S→1\mathrm{P} \rightarrow 3, \mathrm{Q} \rightarrow 2, \mathrm{R} \rightarrow 4, \mathrm{~S} \rightarrow 1

  3. Option C:

    P→3,Q→4,R→2, S→1\mathrm{P} \rightarrow 3, \mathrm{Q} \rightarrow 4, \mathrm{R} \rightarrow 2, \mathrm{~S} \rightarrow 1

    Correct
  4. Option D:

    P→1,Q→2,R→5, S→3\mathrm{P} \rightarrow 1, \mathrm{Q} \rightarrow 2, \mathrm{R} \rightarrow 5, \mathrm{~S} \rightarrow 3

Answer: C

Step-by-step solution

(1) radiation at peak λ=hc4eV=1.24×10−64=0.31×10−6=3100 A∘\lambda=\frac{\mathrm{hc}}{4 \mathrm{eV}}=\frac{1.24 \times 10^{-6}}{4}=0.31 \times 10^{-6}=3100 \mathrm{~A}^{\circ}

λm T=2.9×10−3\lambda_{\mathrm{m}} \mathrm{~T}=2.9 \times 10^{-3} λm=2.9×10−3 T=3100×10−10\lambda_{\mathrm{m}}=\frac{2.9 \times 10^{-3}}{\mathrm{~T}}=3100 \times 10^{-10} T=2.9×1073100=9354 K→10000 K\mathrm{T}=\frac{2.9 \times 10^{7}}{3100}=9354 \mathrm{~K} \rightarrow 10000 \mathrm{~K}

(2) λm\lambda_{m} visible to human eye (violet to red) (For 700 nm ) T=2.9×10−37000×10−10=290007=4142→5000 K\mathrm{T}=\frac{2.9 \times 10^{-3}}{7000 \times 10^{-10}}=\frac{29000}{7}=4142 \rightarrow 5000 \mathrm{~K} (For 400 nm ) T=2.9×10−34000×10−10=7250\mathrm{T}=\frac{2.9 \times 10^{-3}}{4000 \times 10^{-10}}=7250 (3) widest central maximum ⇒λmax⁡⇒Tmin⁡⇒2000 K\Rightarrow \lambda_{\max } \Rightarrow \mathrm{T}_{\min } \Rightarrow 2000 \mathrm{~K} (4) power per unit area =116=\frac{1}{16} (power by block body at T=6000 K\mathrm{T}=6000 \mathrm{~K} )

=116σ(6000)4=σT4⇒ T=3000 K=\frac{1}{16} \sigma(6000)^{4}=\sigma \mathrm{T}^{4} \Rightarrow \mathrm{~T}=3000 \mathrm{~K}

(5) λ=1 A0\lambda=1 \stackrel{0}{\mathrm{~A}}

T=2.9×10−310−10=2.9×107 K\mathrm{T}=\frac{2.9 \times 10^{-3}}{10^{-10}}=2.9 \times 10^{7} \mathrm{~K}

(p) →3\rightarrow 3, (q) →4\rightarrow 4, (r) →2\rightarrow 2, (s) →1\rightarrow 1

Answer key and solution verified before publishing.

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Exam
JEE Advanced 2023
Paper
Paper 1
Subject
Physics
Chapter
Heat Transfer
Topic
Convection and Radiation