A helium–neon laser emits a continuous beam of light with a wavelength of and an…

PHYSICS · Single correct · A Level · Physics · Particles and radiation · Particles and radiation

Problem

A helium–neon laser emits a continuous beam of light with a wavelength of

632\,\text{nm}

and an output power of

2.0\,\text{mW}

. Approximately how many photons does the laser emit each second? (a)

4.0\times10^{16}

(b)

6.4\times10^{18}

(c)

6.4\times10^{15}

(d)

3.2\times10^{15}