The following graph shows the variation of photocurrent for a photosensitive metal :

(a) Identify the variable $\mathit{X}$ on the horizontal axis.
(b) What does the point $\mathrm{A}$ on the horizontal axis represent?
(c) Draw this graph for three different values of frequencies of incident radiation ${\mathit{v}}_1,{\mathit{v}}_2$ and ${\mathit{v}}_3\left({\mathit{v}}_1>{\mathit{v}}_2>{\mathit{v}}_3\right)$ for same intensity.
(d) Draw this graph for three different values of intensities of incident radiation ${\mathit{I}}_1,{\mathit{I}}_2$ and ${\mathit{I}}_3$ $\left({\mathit{I}}_1>{\mathit{I}}_2>{\mathit{I}}_3\right)$ having same frequency.