The surface of a metal is illuminated with a light of wavelength 400 nm . The maximum kinetic energy of the ejected photoelectrons was found to be 1.68 eV . The work function of the metal is (h c = 1240 e V n m)

Question

The surface of a metal is illuminated with a light of wavelength 400 nm . The maximum kinetic energy of the ejected photoelectrons was found to be 1.68 eV . The work function of the metal is (h c = 1240 e V n m) (A) 3.09 eV (B) 1.41 eV (C) 1.51 eV (D) 1.68 eV

Tardigrade Admin · Accepted Answer

∵ (h c/λ )=(1/2)mv2+φ ⇒ φ=(h c/λ )-(1/2)mv2 φ=(1240/400)-1.68=1.41 eV

Q. The surface of a metal is illuminated with a light of wavelength $400 nm$ . The maximum kinetic energy of the ejected photoelectrons was found to be $1.68 e V$ . The work function of the metal is $(h c = 1240 e V nm)$

$3.09 e V$

$1.41 e V$

$1.51 e V$

$1.68 e V$

$∵ \frac{h c}{λ} = \frac{1}{2} m v^{2} + ϕ$
$\Rightarrow ϕ = \frac{h c}{λ} - \frac{1}{2} m v^{2}$
$ϕ = \frac{1240}{400} - 1.68 = 1.41 e V$

Q. The surface of a metal is illuminated with a light of wavelength 400nm . The maximum kinetic energy of the ejected photoelectrons was found to be 1.68eV . The work function of the metal is (hc=1240eVnm)

3.09eV

1.41eV

1.51eV

1.68eV