38. An object 5.0 cm high is placed at the 20 cm mark on a metre stick optical bench. A converging lens with a focal length of 20 cm is mounted at the 50 cm mark. What are the position and size of the image relative to the metre stick? (110 cm, -10 cm] 39. A camera lens has a focal length of 6.0 cm and is located 7.0 cm from the film. How far from the lens is the object positioned if a clear image has been produced on the film? (42 cm) 40. Using the "rules for light rays" sketch ray diagrams for the following lenses. State whether the image is: Real or virtual, erect or inverted, and larger or smaller than the object 21 21 21 2f Lesson 6: Diffraction and Interference 41. Yellow light of wavelength 615 mm is incident on a double slit where slits are 1.3 mm apart. At what angle will the fifth order antinodal line appear? (0.14") 42. Light of frequency 6.09 x 10"* Hz is incident on a pair of straight parallel slits and produces an interference pattern on a screen 7.00 m away. If the fringe spacing on the screen is 2.50 cm, determine the distance between the slits. (0.138 mm)43. Light of frequency 4.6 x 10" Hz is incident on a pair of straight parallel slits where the slits are 0.16 mm apart. It creates an interference pattern on a screen 8.0 m away. What is the distance from the centre of the pattern to the fourth bright line? (0.13 m) 44. A flat observation screen is placed at a distance of 4.5 m from a pair of slits. The separation on the screen between the central bright fringe and the first order bright fringe is 0.037 m. The light illuminating the slits has a wavelength of 490 nm. Determine the slit separation. (6.0 x 10> m) 45. In a Young's double slit experiment the separation between the central bright fringe and the first order bright fringe is 2.40 cm for 475 nm light. Assuming that the angles that locate the fringes on the screen are small, find the separation between fringes when light has a wavelength of 611 nm. (3.09 cm) 46. In a Young's double-slit experiment, the angle that locates the second-order bright fringe is 2.0". If the slit separation is 3.8 x 103 m, what is the wavelength of the light? (6.6 x 10" m) 47. Red light of wavelength 600 nm passes through two parallel slits. Nodal lines are produced on a screen 3.0 m away. The distance between the first and tenth nodal lines is 5.0 cm. What is the separation of the slits? (3.24 x 10 m) 48. In an interference experiment, red light with a wavelength of 6.0 x 10" m passes through a double slit. On a screen 1.5 m away, the distance between the 1" and 11" dark bands is 2.0 cm. a. What was the separation between the slits? (4.5 x 10* m) b. What would the spacing be between adjacent nodal lines if blue light (450 nm) were used? (1.5 x 10 3m) 49. Green light of wavelength 5000 A (1 A = 10 m) is shone on a grating and a second order image is produced at 32". How many lines/cm are marked on the grating? (5300 lines/cm) 50. How many lines per metre does a diffraction grating have if the 2" order minimum occurs at an angle of deviation of 16.0' when 530 nm light is used? (3.47 x 105 lines/m) 51. 650 nm yellow light is incident on a diffraction grating which has 150 lines/cm. What is the spacing between the bright fringes produced as a result on a screen 4.9 m away? (4.8 cm] 52. Light of frequency 5.0 x 10" Hz falls on a diffraction grating which has 4.2 x 10" lines/cm. At what angle will the third antinodal line be inclined to the forward direction? (49") 53. A grating is ruled with 1000 lines/cm. How many orders of spectra are possible on either side of the central maximum for 700 nm red light. (14) 54. A light ray of frequency 5.0 x 10* Hz is incident on a diffraction grating that has 180 lines/cm. After passing through the grating the light travels 4.0 m in a trough of water to a screen where it produces an interference pattern. How far apart are the bright fringes on the screen? (Note: neuter = 1.33 and n = c/v ) (3.2 cm)