Question

Question #eab08

Answer 1

By photoelectric equation of Einstein we have

`E=phi_o + K_"max"`

Where
`phi_o ->"photoelectric work function"`

`E-> "enrgy of photon absorbed"`

`K_"max"-> "maximum KE of emitted electron"`

Inserting `phi_o = 1.9ev and E=2.1ev` in the equation we get

`2.1=1.9+ K_"max"`

`=>K_"max"=0.2ev`

If KE is doubled then the value of E will be E'

`E'=phi_o + 2xxE_"max"`

`E'=1.9+2xx0.2=2.3ev`

So the energy of photon to be enhanced by `(E')/E=2.3/2.1=23/21`times to get the KE of photoelectron doubled.