Modern Physics 41. Explain the photoelectric effect and its significance. (3 marks) 42. Calculate the energy of a photon with a wavelength of 500 nm. (Use h = 6.63 x 10^-34 Js and c = 3 x 10^8 m/s) (3 marks) 43. Describe the structure of an atom according to the Bohr model. (3 marks) 44. Explain the concept of nuclear fission and fusion. (3 marks) 45. What is Heisenberg's uncertainty principle? Provide an example. (3 marks) 46. Describe the differences between conductors, insulators, and semiconductors. (3 marks) 47. Explain the concept of wave-particle duality. (3 marks) 48. What are quarks? Describe their role in particle physics. (3 marks) 49. Calculate the binding energy of a nucleus with a mass defect of 0.1 u. (Use 1 u = 931.5 MeV/c2) (3 marks) 50. Describe the significance of the Higgs boson in the Standard Model of particle physics. (3 marks)