(i) In the Davisson-Germer Experiment, what will be Bragg Scattering angle Φ (first order) for an electrons? beam when scattered / diffracted from the surface of Ni-crystal with atomic- planes spacing D = 0.215 nm and the kinetic energy of the e-beam is similar to ~75 eV.
(ii) What is uncertainty Principle? Express it briefly.
(iii) Laser pulses of femtosecond (10^-15 s) can be produced but is makes no sense of talking about color of such pulses. To appreciate this, calculate the time duration of a laser pulse whose range of frequency covers visible spectrum, 40x10^14 to 7.5x10^14 Hz.