Dual Nature of Radiation and Matter — Prelims Questions

Monochromatic light of frequency $6.0 \times 10^{14},\text{Hz}$ is produced by a laser. The power emitted is $2.0 \times 10^{-3},\text{W}$. What is the number of photons emitted per second? (Given Planck's constant $h = 6.63 \times 10^{-34},\text{Js}$)

The work function of a metal is $3.0,\text{eV}$. What is the threshold frequency for this metal? (Given Planck's constant $h = 6.63 \times 10^{-34},\text{Js}$, $1,\text{eV} = 1.6 \times 10^{-19},\text{J}$)

An electron is accelerated through a potential difference of $V,\text{volts}$. Its de Broglie wavelength is $lambda$. If the potential difference is increased to $4V,\text{volts}$, what will be the new de Broglie wavelength?

Which of the following statements is INCORRECT regarding the photoelectric effect?

If the momentum of a particle is doubled, how does its de Broglie wavelength change?

In the Davisson-Germer experiment, the diffraction pattern of electrons confirmed their wave nature. What was the key observation that supported this conclusion?