Calculate the critical angle for the light traveling from glass (n glass= air 1.53) to air (n =1.00). Express your answer in degrees. Normal format with 3 SF. QUESTION 20 An object is placed 8.1cm in front of a converging lens with a focal length of 18.4cm. Use calculation to find the location (in cm) of the image. Normal format with 3 SF. QUESTION 21 In Young's double-slit interference experiment, it is found that the second bright fringe is at the angle of 12.5. If the separation between the double slits is 1.50x 10-3 mm, find the wavelength (in m) of the light source. Exponential format with 3 SF. QUESTION 22 In Young's double-slit interference experiment, it is found that the third dark fringe is at the angle of 17.5. If the separation between the double slits is 1.0x 10-31 mm, find the wavelength (in m) of the light source. Exponential format with 3 SF.