Light of wavelength 2475 Å is incident on barium. Photoelectrons emitted describe a circle of radius 100 cm by a magnetic field of flux density 1 17 10⁻⁵ tesla. The value of work function of the barium is ........ eV. . given, . e m =1.7 10¹¹ )

Step-by-step solution

Radius of circular path described by a charged particle in a magnetic field B is given by r= 2 m K q B K= q^2 B^2 r^2 2 m = ( e m ) e B^2 r^2 2 where, K= kinetic energy of a particle q= charge on a particle r= radius of circular path = 1 2 1.7 10¹¹ 1.6 10⁻¹⁹ ( 1 17 10⁻⁵ )^2 (1)^2=8 10⁻²⁰ ~J =0.5 eV Using the relation, E= +K_ =E-K_ where, E=h v= h c = 12375 ( in Å) = ( 12375 2475 ) eV -0.5 eV =4.5 eV