Question

The graph shown in the figure represents energy density $E_{\lambda }$ versus $\lambda$ for three sources sun, welding age and tungsten filament. For ${\lambda }_{max}$, correct combination will be

• A. $1-tungsten,2-weldingarc,3-sun$
• B. $1-sun,2-tungsten,3-weldingarc$
• C. $1-sun,2-weldingarc,3-tungsten$
• D. $1-weldingarc,2-sun,3-tungsten$

Answer 1

The correct option is A $1-tungsten,2-weldingarc,3-sun$

According to Wien's law the wavelength $\left({\lambda }_m\right)$ corresponding to which energy emitted per sec area by a perfectly back body is maximum, is inversely proportional to the absolute temperature $\left(T\right)$ of the black body. Temperature of sun would be maximum of the given three.
As ${\lambda }_{m}T=constant$
So ${\lambda }_m$ for the sun is minimum i.e. correct answer is (a).