In a photoemissive cell, with exiciting wavelength is changed to `(33lambda)/(4)`, the speed of the fastest emitted electron will be

Options

A. `v(3//4)^(1//2)`
B. `v(4//3)^(1//2)`
C. Less than v `(4//3)^(1//2)`
D. Greater than v `(4//3)^(1//2)`

Answer

D

Explanation

`1/2mv^2=(hc)/lamda-(hc)/lamda_0`
`impliesv=sqrt((2)/m[(hc)/lamda-(hc)/lamda_0])" "...(i)`
as `lamda. = (3lamda)/4`
`v.=sqrt((2hc)/m[(1)/(3lamda//4)-1/lamda_0])`
`v.=(4/3)^(1/2)sqrt((2hc)/m[(1)/(lamda)-3/(4lamda_0)])" "...(ii)`
On dividing equation (i) and (ii)
`v. gt v (4/3)^(1/2)`