Question

Variation of radiant energy emitted by sun, filament of tungsten lamp and welding arc as a function of its wavelength is shown in figure. Which of the following option is the correct match? (IIT JEE 2005)

• A. Sun - $T_3$, tungsten filament - $T_1$, welding are - $T_2$
• B. Sun - $T_2$, tungsten filament - $T_1$, welding are - $T_3$
• C. Sun - $T_3$, tungsten filament - $T_2$, welding are - $T_1$
• D. Sun - $T_1$, tungsten filament - $T_2$, welding are - $T_3$

Answer 1

The correct option is A

Sun - $T_3$, tungsten filament - $T_1$, welding are - $T_2$

According to Wein's displacement law $\lambda m\times T$ = Constant

Here $\lambda m<\lambda m2<\lambda m1$ $\Rightarrow T_3>T_2>T_1$

The temperature of Sun is higher than that of welding arc which in turn is greater than tungsten filament.
Therefore $T_3$ is the Sun's temperature, $T_2$ the welding arc's and $T_1$ the tungsten filament's.