A student performs an experiment to observe photoelectric effect by shining light on a metal surface. The light source limits light of wavelength 450nm. The table given below lists the available metals and their corresponding work functions
Metalϕ(ev)Tungsten4.5Lithium2.3Barium2.5Tantalum4.2
Which of the above metals can be used to produce electrons by the photoelectric effect from the given source of light?
Barium or Lithium
Energy of incident photon =1240ev−nmλ(nm)
=(1240450)eV=2.75eV
For photoelectric effect,
Eincident>ϕ