1) Students perform an experiment they shine a laser through a diffraction grating and observe and interference pattern on the wall. The distance between the lines for the diffraction grating is 1.54 x 10-6m. The students measure the distance from the central bright spot to the first antinode and record 62.3 cm when the diffraction grating is 1.70m from the wall. A) Draw a basic diagram and describe and explain in two sentences why bright spots occur? B) Determine the lines per millimetre on the diffraction grating. C) Determine the wavelength of the laser. D) The student decides to use a laser with a lower wavelength. Would the bright spots on the interference pattern ... get closer, stay the same, or mover further apart. (circle one) 2) A red laser with wavelength 680 nm is shone through two slits and an interference pattern is observed on the wall 2.40 m away. The third bright spot is 8.32 cm from the central bright spot. Determine the distance between the openings on the double slit. 3) Light with wavelength 140 nm is incident on a metal surface with threshold frequency 8.40 x1014 Hz. Determine the following... Work function of metal in ev Speed of photo-emitted electrons in m/s . Stopping voltage required to slow down photo-emitted electrons in Volts