Question

If the wavelength of incident light changes from $300nmto400nm$, then find the change in sloping potential. If the work function of metal$=2.5eV$?

• A. $1.03eV$
• B. $2.10eV$
• C. $1.85eV$
• D. $2.03eV$

Answer 1

The correct option is A

$1.03eV$

Step 1: Given data

The wavelength of incident light changes from $\lambda =300nmto400nm$.

Step 2: Formula used

Know that the formula for stopping potential

$e{V}_0=\frac{hc}{\lambda }-\varphi$ here, $e$energy of photon, $V_0$ is the frequency of the electromagnetic radiation and $\lambda$ is the wavelength.

Step 3: Find the change in sloping potential

Now for the wavelength $\lambda =300nm$

Therefore,

$$\begin{gathered} e{V}_1=\frac{hc}{300nm}-\varphi \\ e{V}_2=\frac{hc}{400nm}-\varphi \end{gathered}$$

Therefore the change in stopping potential.

$$\begin{gathered} e\left(V_1-V_2\right)=1240\left(\frac{100}{300\times 400}\right) \\ e\left(V_1-V_2\right)=1.03eV \end{gathered}$$

Therefore the change in sloping potential $1.03eV$.

Hence, the correct option is (A).