197. In a photoelectric experiment, the graph shows the kinetic energy changes of the fastest photoelectrons emitted from two metals A and B as a function of incident light frequency. According to the graph, the threshold frequencies of metals A and B are $f_A$ and $f_B$ respectively, and the maximum speeds of photoelectrons emitted from these two metals are equal. If $\dfrac{f_B}{f_A} = n$, which answer is correct? [Figure: Graph of $K_{\max}$ vs. $f(10^{15}\ \text{Hz})$ showing two lines A and B with x-intercepts at approximately 0.5 and 1] \begin{flushright} (1) $1 < n < 2$ (2) $n = 1$ (3) $n = \dfrac{1}{2}$ (4) $\dfrac{1}{2} < n < 1$ \end{flushright}
\textbf{197.} In a photoelectric experiment, the graph shows the kinetic energy changes of the fastest photoelectrons emitted from two metals A and B as a function of incident light frequency. According to the graph, the threshold frequencies of metals A and B are $f_A$ and $f_B$ respectively, and the maximum speeds of photoelectrons emitted from these two metals are equal. If $\dfrac{f_B}{f_A} = n$, which answer is correct?
\begin{center}
\textit{[Figure: Graph of $K_{\max}$ vs. $f(10^{15}\ \text{Hz})$ showing two lines A and B with x-intercepts at approximately 0.5 and 1]}
\end{center}
\begin{flushright}
(1) $1 < n < 2$\\
(2) $n = 1$\\
(3) $n = \dfrac{1}{2}$\\
(4) $\dfrac{1}{2} < n < 1$
\end{flushright}