Question

In determining the temperature of a distant star, one makes use of
A. Kirchhoff’s law
B. Stefan’s law
C. Wien’s displacement law
D. None of these

Answer 1

A higher temperature causes the wavelength of peak emission to be at a shorter wavelength. In order to find the solution of the given question we will check the concept of each option, then choose the correct answer.

Complete step by step answer:
Kirchhoff’s law is used to calculate the electrical resistance of a complex network or impedance in alternating currents case and the current flow in different streams of the network.
Stefan’s Boltzmann law or Stefan’s law describes that the total energy radiated per unit surface area of a body across all the wavelengths per unit time is directly proportional to the black body’s fourth power of thermodynamic temperature.
Wein’s law which is named after the German Physicist Wilhelm Wien, describes that the objects of different temperatures emit spectra that peak at different wavelengths. Objects which are hotter emit radiations of shorter wavelength and hence, they appear blue. Similarly, objects which are cooler emit radiations of longer wavelength and hence they appear reddish in colour.
Wein’s displacement states that the black body radiation consists of different peaks of temperature at wavelengths that are inversely proportional to temperatures.
Mathematically, it can be written as
$\lambda = \dfrac{b}{T}$ ; where ‘b’ is the Wien’s displacement constant and ‘t’ is the temperature in kelvin Therefore, in determining the temperature of a distant star, one makes use of the Wein’s law.

So, the correct answer is “Option C”.

Note:
For a better understanding of the concept we can list some applications of Wein’s law in our day to day life. In incandescent light bulbs with decrease in the temperature of the filament, longer wavelengths make the light appear reddish. Temperature of the sun or stars can be studied using this law.