Direction for: In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
Assertion Mass of moving photon varies inversely as the wavelength. Reason Energy of the particle = mass x (speed of light)2A) If the Assertion and Reason are true and Reason is the correct explanation of Assertion
B) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
C) If Assertion is true but Reason is false
D) If both Assertion and Reason are false
Correct Answer: B
Solution :
Einstein by his theory of relativity proved that mass and energy are related to each other and every substance has energy due to its mass also. If a substance losses an amount \[\Delta M\] of mass, an equivalent amount\[\Delta E\] of energy is produced given by \[\Delta E=m{{c}^{2}}\] ?(i) where, c is speed of light. This is called Einstein. mass-energy relation. Also energy E = hv ... (ii) where h is Plancks constant and v is frequency Also, \[v=-\frac{c}{\lambda },\]where c is speed of light and \[\lambda \] is wavelength. Hence, \[E=\frac{hc}{\lambda }\] \[E\propto \frac{1}{\lambda }\] From Eqs. (i) and (ii), mass of photon varies inversely as the wavelength.
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