Optics Answers

 Explain why light can be polarized but sound cannot.

  (a.) Differentiate between interference and diffraction of light.

            (a.) Light of wavelength 5.5 × 10^-7m falls on a single silt of width 0.15mm. A screen is placed 1.2m beyond the slit.

             (i.) Name the phenomenon that occurs.

              (ii) Sketch a graph showing the light pattern observed on the screen.

             (iii.) Calculate the width of the central fringe.

            A grating has 600 lines per mm and is illuminated norn1ally by light of wavelength 590nm.

            (a.) Find the direction of the first-order diffraction image.

            (b.) Is it possible to obtain a third-order image with this diffraction grating for this wavelength?

            (c.) What would be the effect on the number of orders, if the wavelength of the wave is increased?

Light is incident normally on a diffraction grating of 5000 lines per centimeter and a second-order image is obtained at an angle of 36°.

            (a.) Calculate the wavelength of the light used, (b.) Determine whether a third-order image can be obtained with light of the same wavelength. (c.) State and explain in which the number of orders can be increased.

 A parallel beam of red light of wavelength 650nm arrives normally at a diffraction grating. The first order maximum has an angle of 40°. Calculate the total number of principal maxima this grating can produce for the red light. At what angle is the highest order maxima produced?

In a location where the speed of sound in air is 354ms^-1, a 200Hz sound wave impinges on two slits 30.0cm apart.

           a.) At what angle is the first maximum located?

           b.) If the sound is replaced by a 3.00cm microwave, what slit separation gives the same angle for the first maximum?

  A source emitting light of two wavelengths is viewed through a grating spectrometer set at normal incidence. When the telescope is set at an angle of 20° to the incident direction, the second-order maximum for one wavelength is seen superposed on the third-order maximum for the other wavelength. The shorter wavelength is 400nm. Calculate the longer wavelength and the number of lines per centimeter in the grating. At what other angles, if any, can the superposition of two orders be seen using this source?

 A diffraction grating produces a second-order principal maximum at 50.6° to the normal when being illuminated normally with light of wavelength 644nm. Calculate the number of lines per millimeter of the grating and the total number of principal maxima produced.

          A diffraction grating has 1.2 × 10⁴ rulings or lines uniformly spaced over a width w = 25.4mm. This grating is illuminated at normal incidence by yellow light from a sodium vapour lamp of wavelength 589nm. Determine the greatest angle at which an order can occur on either side of the center of the diffraction pattern?