What is the geometrical shape of wavefront of light emerging out of a convex lens when a point source is placed at its focus ?

What is the shape of the wavefront in each of the following cases : light diverging from a point source

What is the shape of a wavefront emitted by a light source in the form of a narrow slit ?

When a plane wavefront is incident on a double convex lens, the refracted wavefront is

If the object is at infinity from a convex lens, what would be its size?

Answer the following questions : When an object of height 2 cm is placed in front of a convex lens, the height of the image is found to be 3cm . State the nature and position of the image giving reason .

Find the focal length of a convex lens which produces a real image at 60 cm from the lens when an object is placed at 40 cm in front of the lens .

Find the focal length of a convex lens which produces a virtual image at 10 cm from the lens when an object is placed at 5 cm from the lens .

Consider a point at the focal point of a convergent lens. Another convergent lens of short focal length is placed on the other side. What is the nature of the wavefronts emerging from the final image?

Answer the following questions A plane mirror is kept at the bottom of a trough with water in it as show in the following figure . The ray of light emerging from a source at the point S outside the trough, reaches the point A on the surface of water. Draw a neat ray diagram to show the subsequent path of light and complete the ray diagram.

What is wavefront ? What is the shape of the wavefront at a point far away from the source of light?