The maximum velocity of an electron emitted by light of wavelength $\lambda$ incident on the surface of a metal of work function $\phi$ is (Where $h =$ Planck's constant,$m =$ mass of electron,and $c =$ speed of light).

Radiations of two photons having energies twice and five times the work function of a metal are incident successively on a metal surface. The ratio of the maximum velocity of photoelectrons emitted in the two cases will be

The maximum velocity of an electron emitted by light of wavelength $\lambda$ incident on the surface of a metal of work function $\phi$ is:
Where $h =$ Planck's constant, $m =$ mass of electron, and $c =$ speed of light.

$A$ metal plate of area $1 \times 10^{-4} \, m^2$ is illuminated by radiation of intensity $16 \, mW/m^2$. The work function of the metal is $5 \, eV$. The energy of the incident photons is $10 \, eV$ and only $10\%$ of the incident photons produce photoelectrons. The number of emitted photoelectrons per second and their maximum kinetic energy, respectively, will be: $[1 \, eV = 1.6 \times 10^{-19} \, J]$

$A$ silver sphere of radius $1 \ cm$ and work function $4.7 \ eV$ is suspended from an insulating thread in free space. It is under continuous illumination of $200 \ nm$ wavelength light. As photoelectrons are emitted,the sphere gets charged and acquires a potential. The maximum number of photoelectrons emitted from the sphere is $A \times 10^Z$ (where $1 < A < 10$). The value of $Z$ is:

Assertion : When ultraviolet light is incident on a photocell,its stopping potential is $V_0$ and the maximum kinetic energy of the photoelectrons is $K_{max}$. When the ultraviolet light is replaced by $X-$ rays,both $V_0$ and $K_{max}$ increase.
Reason : Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light.