$10^{20}$ photons of wavelength $660 \ nm$ are emitted per second from a lamp. The wattage of the lamp is (Planck's constant $h = 6.6 \times 10^{-34} \ J \cdot s$). (in $W$)

If sources of ultraviolet $(\lambda \approx 400 \ nm)$,visible $(\lambda \sim 550 \ nm)$,and infrared $(\lambda \sim 700 \ nm)$ radiation each have a power rating of $100 \ W$,then the number of photons emitted per unit area per unit time is maximum for:

The relationship between the velocity and frequency of a photon in a vacuum is represented by a ...... .

$A$ $100\,W$ light source is emitting radiation of wavelength $5000\,\mathring{A}$. The rate of emission of photons is of the order of:

The Compton effect supports the fact that

Show that the wavelength of electromagnetic radiation is equal to the de Broglie wavelength of its quantum (photon).