Circle the author's purpose for writing this passage

State one advantage and one disadvantage of using a plane mirrior as a driving mirrior

If the ama of the inclined plane below is 2, calculate the ima and efficiency. ima = efficiency =

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?