A photon carries an energy of $3.11 \times 10^{-19}\,\text{J}$. Calculate the momentum of the photon.
A laser beam has a power of $350\,\text{mW}$. Its light has a wavelength of $640\,\text{nm}$. Determine the number of photons emitted by the laser in a time of $1.0\,\text{s}$.
A laser beam strikes a surface at right angles, and the surface absorbs every photon. Show that the force $F$ on the surface caused by the laser beam is given by $F = \frac{P}{c}$, where $P$ is the power of the laser beam and $c$ is the speed of light.
Light of a single wavelength falls on the surfaces of different metals. The work function energy values of the metals are listed in Table 7.1. Explain the term threshold wavelength.
For the metals in Table 7.1, calculate the largest threshold wavelength.