The figure represents the graph of photocurrent $I$ versus applied voltage $(V)$. The maximum kinetic energy of the emitted photoelectrons is:

For a certain metal, when monochromatic light of wavelength $\lambda$ is incident, the stopping potential for photoelectrons is $3V_0$. When the same metal is illuminated by light of wavelength $2\lambda$, then the stopping potential becomes $V_0$. The threshold wavelength for photoelectric emission for the given metal is $\alpha\lambda$. The value of $\alpha$ is . . . . . . .

The frequency and the intensity of a beam of light falling on the surface of a photoelectric material are both increased by a factor of two. This will:

$A$ stream of photons having energy $3 \,eV$ each impinges on a potassium surface. The work function of potassium is $2.3 \,eV$. The emerging photo-electrons are slowed down by a copper plate placed $5 \,mm$ away. If the potential difference between the two metal plates is $1 \,V$,the maximum distance the electrons can move away from the potassium surface before being turned back is .......... $mm$.

Ultraviolet light of wavelength $2271 \,\mathring{A}$ from a $100 \; W$ mercury source irradiates a photo-cell made of molybdenum metal. If the stopping potential is $-1.3 \; V$, estimate the work function of the metal. How would the photo-cell respond to a high-intensity $(10^{5} \; W \; m^{-2})$ red light of wavelength $6328 \,\mathring{A}$ produced by a $He-Ne$ laser?

Which one of the following graphs correctly represents the variation of maximum kinetic energy $(E_{k})$ of the emitted electrons with frequency $(\nu)$ of incident light in the photoelectric effect?