Question

The figure shows the variation of photocurrent with anode potential for a photo-sensitive surface for three different radiations. Let $I_{a}, I_{b}$ and $I_{c}$ be the intensities and $v_{a}, v_{b}$ and $v_{c}$ be the frequencies for the curves $a, b$ and $c$ respectively. Then,

• A. $v_{a}=v_{b}$ and $I_{a} \neq I_{b}$
• B. $v_{a}=v_{c}$ and $I_{a}=I_{c}$
• C. $v_{a}=v_{b}$ and $I_{a}=I_{b}$
• D. $v_{b}=v_{c}$ and $I_{b}=I_{c}$

Answer 1

Answer: (A)

From the graph, we note that the saturation current is same for curves $b$ and $c$ but different for curve $a$. Therefore, intensities of $b$ and $c$ will be equal but different from that of $a$ i.e. $I_{a} \neq I_{b}$ but $I_{b}=I_{c}$. As stopping potential is same for curves $a$ and $b$, hence $v_{a}=v_{b}$. Thus answer (a) is correct.