The wavelength of red light is about 760 nm. The work functions of Cs , Na , Cu and Pt are 2.14 eV , 2.75 eV 4.65 eV and 5.65 eV respectively. Which among the following metals can be used as a photosensitive material for red light

Question

The wavelength of red light is about 760 nm. The work functions of Cs , Na , Cu and Pt are 2.14 eV , 2.75 eV 4.65 eV and 5.65 eV respectively. Which among the following metals can be used as a photosensitive material for red light (A) Cs , Na , Cu , Pt (B) Cs, Na only (C) Cu , Pt only (D) none of them.

Tardigrade Admin · Accepted Answer

E=(h c/λ), E red =(1242 eV - nm /760 nm )=1.63 eV As E text red is less than the work function of all the metals given in the question, none of the metals will be photosensitive to it.

Q. The wavelength of red light is about $760 nm$ . The work functions of $C s, N a, C u$ and $Pt$ are $2.14 e V, 2.75 e V$ $4.65 e V$ and $5.65 e V$ respectively. Which among the following metals can be used as a photosensitive material for red light

$C s, N a, C u, Pt$

$C s, N a$ only

$C u, Pt$ only

none of them.

$E = \frac{h c}{λ}, E_{re d} = \frac{1242 e V - nm}{760 nm} = 1.63 e V$
As $E_{red}$ is less than the work function of all the metals given in the question, none of the metals will be photosensitive to it.

Q. The wavelength of red light is about 760nm. The work functions of Cs,Na,Cu and Pt are 2.14eV,2.75eV 4.65eV and 5.65eV respectively. Which among the following metals can be used as a photosensitive material for red light

Cs,Na,Cu,Pt

Cs,Na only

Cu,Pt only