CBSE Class 12-science Answered

ques1: In a photo-emissive cell, with exciting wavelength λ, the maximum kinetic energy of electron is K. If theexciting wavelength is changed to 3λ/4, the kinetic energy of the fastest emitted electron will be:(A) 3K/4 (B) 4K/3 (C) less than 4K/3 (D) greater than 4K/3



ques 2: An electron with initial kinetic energy of 100 eV is acceleration through a potential difference of 50 V.Now the de-Broglie wavelength of electron becomes: (A) 1 Å (B) 5.1 Å (C) 3 Å (D) 12.27 Å




ques 3: The stopping potential for the photo electrons emitted from a metal surface of work function 1.7 eV is 10.4 V. Identify the energy levels corresponding to the transitions in hydrogen atom which will result in emission of wavelength equal to that of incident radiation for the above photoelectric effect: (A) n = 3 to 1 (B) n = 3 to 2 (C) n = 2 to 1 (D) n = 4 to 1