A $1.0 \mathrm{mW}$ laser produces red light of wavelength $6.48\times {10}^{-7}\mathrm{m}$. Calculate how many photons the laser produces per second.

With the help of a calculation, identify the region of the electromagnetic spectrum (Figure) a photon of energy 10 eV belongs.

A proton, initially at rest, is accelerated through a potential difference of $1500\mathrm{V}$. A proton has charge $+1.60\times {10}^{-19}\mathrm{C}$ and mass $1.67\times {10}^{-27}\mathrm{kg}$.

Calculate its final kinetic energy in joules (J)

A proton, initially at rest, is accelerated through a potential difference of $1500\mathrm{V}$. A proton has charge $+1.60\times {10}^{-19}\mathrm{C}$ and mass $1.67\times {10}^{-27}\mathrm{kg}$. Calculate its final speed.

In an experiment to determine the Planck constant $h$, LEDs of different colours were used. The p.d. required to make each conduct was determined, and the wavelength of their light was taken from the manufacturer's catalogue. The results are shown in Table. For each LED, calculate the experimental value for hand, hence, determine an average value for the Planck constant.

Photons of energies $1.0 \mathrm{eV}, 2.0 \mathrm{eV} \& 3.0 \mathrm{eV}$ strike a metal surface whose work function is $1.8 \mathrm{eV}$. State which of these photons could cause the release of an electron from the metal.

Photons of energies $1.0 \mathrm{eV}, 2.0 \mathrm{eV} \& 3.0 \mathrm{eV}$ strike a metal surface whose work function is $1.8 \mathrm{eV}$.

Calculate the maximum kinetic energies of the electrons released in each case. Give your answers in e V and in J.