Question 154: Dual Nature of Matter and Radiation

Question

A monochromatic neon lamp with wavelength of 670.5 nm illuminates a photo-sensitive material which has a stopping voltage of 0.48 V. What will be the stopping voltage if the source light is changed with another source of wavelength of 474.6 nm?

Accepted Answer

$$k{E_{\max }} = {{hc} \over {{\lambda _i}}} + \phi $$
or $$e{V_o} = {{hc} \over {{\lambda _i}}} + \phi $$
when $$\lambda$$
i
= 670.5 nm ; V
o
= 0.48
when $$\lambda$$
i
= 474.6 nm ; V
o
= ?
So,
$$e(0.48) = {{1240} \over {670.5}} + \phi $$ ..... (1)
$$e({V_o}) = {{1240} \over {474.6}} + \phi $$ .....(2)
(2) $$-$$ (1)
$$e({V_o} - 0.48) = 1240\left( {{1 \over {474.6}} - {1 \over {670.5}}} ight)eV$$
$${V_o} = 0.48 + 1240\left( {{{670.5 - 474.6} \over {474.6 	imes 670.5}}} ight)$$ Volts
V
o
= 0.48 + 0.76
V
o
= 1.24 V $$ \simeq $$ 1.25 V

Answer

0.96 V

Answer

1.25 V

Answer

0.24 V

Answer

1.5 V

Dual Nature of Matter and Radiation

A monochromatic neon lamp with wavelength of 670.5 nm illuminates a photo-sensitive material which has a stopping voltage of 0.48 V. What will be the stopping voltage if the source light is changed with another source of wavelength of 474.6 nm?

Choose the correct answer: