# You are heating two chunks of metal of the same size and shape. One is made of lead and is heated to 400 K. The other is made of iron

You are heating two chunks of metal of the same size and shape. One is made of lead and is heated
to 400 K. The other is made of iron and is heated to 350 K. Which of the following statements
apply to the thermal radiation the two chunks emit?

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This question is incomplete without the options but the options are provided below

(a) the two spectra peak at the same wavelength

(b) the spectra cannot be compared because they come from different materials

(c) The lead spectrum peak is at a shorter wavelength than the iron spectrum peak

(d) the lead spectrum peak is at a longer wavelength than the iron spectrum peak

The correct option is c

Explanation:

This question on quantum physics seek to test our knowledge of Wien’s displacement law which states that when different temperatures (in kelvin) of a black body radiator increases, they will peak at different wavelengths which are inversely proportional to the temperature. Hence, an increase in temperature of a black-body object will peak at a shorter wavelength than the other black-body object with a lesser temperature; since the lead was heated to 400 K, it’s spectrum will peak at a shorter wavelength than that of iron which was heated to 350 K.

Hence, the correct option is c