Final answer:
When a parallel beam of light but not parallel to the principal axis strikes a convex lens, the light rays converge to a focal point. When the same beam of light strikes a concave lens, the light rays diverge away from a virtual focal point.
Step-by-step explanation:
When a parallel beam of light but not parallel to the principal axis strikes a convex lens, the light rays converge to a point on the principal axis. This point is called the focal point. On the other hand, when the same beam of light strikes a concave lens, the light rays diverge away from the principal axis. The point where the diverging rays appear to originate from is known as the virtual focal point.
To draw the ray diagrams, follow these steps:
- For a convex lens, draw a horizontal line to represent the principal axis and draw the lens shape.
- Draw the incoming ray at an angle to the principal axis, passing through the lens. Draw the refracted ray from the lens through the principal axis.
- Draw another incoming ray parallel to the principal axis, passing through the lens. Draw the refracted ray through the focal point.
- For a concave lens, follow similar steps but draw the outgoing rays diverging away from the focal point.
Learn more about Convex and concave lenses