The frequency,wavelength,or speed of light does not change on reflection.

$A$ student focused the image of a candle flame on a white screen using a convex lens. He noted down the positions of the candle,screen,and lens as follows:
Position of candle $= 12.0 \, cm$
Position of convex lens $= 50.0 \, cm$
Position of the screen $= 88.0 \, cm$
$(i)$ What is the focal length of the convex lens?
$(ii)$ Where will the image be formed if he shifts the candle towards the lens to a position of $31.0 \, cm$?

What type of image cannot be formed by a convex lens?

$(a)$ $A$ concave mirror produces a three times enlarged real image of an object placed at $10\, cm$ in front of it. Calculate the focal length of the mirror.
$(b)$ Show the formation of the image with the help of a ray diagram when an object is placed $6\, cm$ away from the pole of a convex mirror.

An object is placed at a distance of $12 \ cm$ in front of a concave mirror. It forms a real image four times larger than the object. Calculate the distance of the image from the mirror. (in $cm$)

$A$ ray of light is incident on a plane mirror normally. What are the angle of incidence and the angle of reflection?