5. What is the angle between the incident and reflected rays when a ray of light incident normally on a plane mirror.

The angle will be 0 . The angle between the incident ray and the mirror is called angle of incidence while the angle between reflected ray and the normal is called angle of reflection. Here, the a ray of light is incident normally on a plane mirror.

Explanation:

measuring things 1 litre of water

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west