Question

Statement I : Two photons having equal linear momenta have equal wavelengths. Statement II : If the wavelength of photon is decreased, momentum and energy will also decrease.

• A. Both true
• B. Both false
• C. I true, II false
• D. I false, II true

Hint:

Wavelength is inversely proportional to both energy and momentum for a photon. Shorter wavelength means higher energy.

Answer 1

The Correct Option is C

Step 1: De-Broglie relation: $\lambda = \frac{h}{p} \Rightarrow p = \frac{h}{\lambda}$. If $p$ is equal, $\lambda$ is equal. (I is true).
Step 2: If $\lambda$ decreases, $p$ increases ($p \propto 1/\lambda$) and $E$ increases ($E = hc/\lambda$). (II is false).