$A$ ray of light is incident normally on a reflecting surface. What are the $(i)$ angle of incidence and $(ii)$ angle of reflection?

$A$ beam of light incident on a plane mirror forms a real image on reflection. The incident beam is

Which of the following can produce a magnification of $+0.5$?

What will be the focal length of a lens whose power is given as $+2.0 \ D$?

Identify the device used as a spherical mirror or lens in the following cases,where the image formed is virtual and erect in each case.
$(a)$ Object is placed between the device and its focus,image formed is enlarged and behind it.
$(b)$ Object is placed between the focus and the device,image formed is enlarged and on the same side as that of the object.
$(c)$ Object is placed between infinity and the device,image formed is diminished and between the focus and optical centre on the same side as that of the object.
$(d)$ Object is placed between infinity and the device,image formed is diminished and between the pole and focus,behind it.

State the laws of refraction.