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 $I_a\ne I_b$
• 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. $I_a\ne I_b$ 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.