What is the speed of light waves in a vacuum in units of $km/s$?

What type of lens behaviour will an air bubble inside water show?

$A$ convex mirror can be used to see a large image of a small object.

Which of the following is the correct general form of Snell's law?

Where should an object be placed in front of a convex lens to obtain an image on the same side as the object?

An object of height $5 \, cm$ is placed perpendicular to the principal axis of a concave lens of focal length $10 \, cm$. If the distance of the object from the optical centre of the lens is $20 \, cm$,determine the position,nature,and size of the image formed using the lens formula.