A ray from a fixed object is incident on a plane mirror at an angle of 20o. If the mirror is rotated through 30o by how many degree would the reflected ray rotate?
A travelling microscope is focused on a mark on a table. If a glass block of thickness 18.0cm is placed on the mark by how many centimeters will the microscope be moved upwards so as to focus the mark once again? [refractive index of glass = 1.5]
