Question

We can say that the energy of frequency $v$ is given by $E=hv$, where $h$ is Planck's constant. The momentum of a photon is $p=\frac{h}{\lambda }$ where $\lambda$ is the wavelength of photon. Then we may conclude that velocity of light is equal to:

• A. ${\left(\frac{E}{P}\right)}^{1/2}$
• B. $\frac{E}{P}$
• C. EP
• D. ${\left(\frac{E}{P}\right)}^2$

Answer 1

The correct option is B $\frac{E}{P}$

We know that,
$v=\lambda \times \upsilon$.
$E=h\upsilon ,p=\frac{h}{\lambda }$

Dividing the above 2 equation
$\therefore \frac{E}{p}=\upsilon \times \lambda =c$.
The problem can also be approached by using dimensional analysis.