question_answer

Which of the following statements is true?

A)  If wavelength of light increases then frequency also increases

B)  If energy increases then frequency also increases

C)  Frequency of red light is greater than frequency of blue light

D)  If energy increases then frequency decreases

Correct Answer: B

Solution :

[a] Wavelength of light is related to frequency through the relation,                 \[v=n\lambda \] or            \[n\propto \frac{1}{\lambda }\] So, if wavelength of light increases, then frequency decreases. [b] Energy, \[E=hv\] where h is Plancks constant or            \[E\propto v\] So, if energy increases, then frequency also increases. [c] Visible spectrum has seven colours in the order of letter VIBGYOR. The frequency of colours decreases from violet to red. Hence, frequency of red light is less than frequency of blue light. [d] This statement is wrong as explained in option [b]