Light of wavelength 2475A0  is incident on Barium. Photoelectrons emitted describe a circle of radius 100 cm by a magnetic field of flux density 117×10−5Tesla. The workfunction of Barium is (Given em=1.7×1011 C/Kg)

Radius of circular path described by the charged particle in the given magnetic field isr=2mKEqBKE=q2B2r22m=em×eB2r22       =1.7×1011×12×1.6×10−19×117×10−52×12       =8×10−20J       =0.5 eVBy using the relation, W0=E−KEmax=124002475−0.5=4.5eV