Photo cells are used for the:

Photoelectric effect experiments are performed using three different metal plates $p, q$ and $r$ having work functions $\phi_p=2.0 \ eV, \phi_q=2.5 \ eV$ and $\phi_r=3.0 \ eV$,respectively. $A$ light beam containing wavelengths of $550 \ nm, 450 \ nm$ and $350 \ nm$ with equal intensities illuminates each of the plates. The correct $I-V$ graph for the experiment is:

According to the particle theory of light (Newton's corpuscular theory),what is the velocity of light in a dense medium compared to that in a rare medium?

An electron of mass $m$ and a photon have the same energy $E$. The ratio of the wavelength of the electron to that of the photon is: ($c$ being the velocity of light)

Which of the following effects support the quantum nature of $EM$ radiation? $(1)$ Photoelectric effect $(2)$ Compton effect $(3)$ Doppler effect $(4)$ Field effect

The spectrum of an oil flame is an example of: