For most metals, threshold frequencies lie in which region?

Assertion : The photoelectrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.
Reason : The work function of the metal varies as a function of depth from the surface.

$A$ convex lens of focal length $40 \ cm$ forms an image of an extended source of light on a photoelectric cell. $A$ current $I$ is produced. The lens is replaced by another convex lens having the same diameter but focal length $20 \ cm$. The photoelectric current now is:

The work function of a metal is defined as:

Monochromatic light with a frequency well above the cutoff frequency is incident on the emitter in a photoelectric effect apparatus. The frequency of the light is then doubled while the intensity is kept constant. How does this affect the photoelectric current?

Light of frequency two times the threshold frequency is incident on a photosensitive material. If the incident frequency is made $\left(\frac{1}{3}\right)^{rd}$ and intensity is doubled,then the photoelectric current will