A ray of light is made incident on a concave mirror, parallel to its principal axis. After reflection it will -
pass through the principal focus
Concave Mirror Reflection: Ray Parallel to Principal Axis
This question concerns the behavior of light when it interacts with a concave mirror. A concave mirror is a type of spherical mirror where the reflective surface curves inwards. The principal axis is a reference line that passes through the center of curvature and the pole of the mirror.
Understanding Reflection of Parallel Rays
When a ray of light travels parallel to the principal axis of a concave mirror, its path after reflection is a fundamental concept in optics. According to the laws governing reflection from curved surfaces:
- Any ray of light incident on a concave mirror parallel to its principal axis, after reflection, converges at a specific point.
The Role of the Principal Focus
This point of convergence is known as the principal focus (often denoted as 'F') of the concave mirror. The principal focus is a characteristic property of the mirror, determining its focal length. The focal length is the distance from the pole of the mirror to the principal focus.
Therefore, a light ray incident on a concave mirror parallel to its principal axis will, after reflection, always pass through the mirror's principal focus.
Considering the given options, the correct path for the reflected ray is to pass through the principal focus.
Important Questions from Mirrors and Images
- A concave mirror forms a real and inverted image of a distant object at a distance of $15 \text{ cm}$ from the mirror.
If an object is placed $20 \text{ cm}$ in front of this mirror, what will be the nature and magnification of the image formed? The number of images observable between two parallel mirror is
Which of the following pair is correct?
I. Mirror formula : (1/v) – (1/u) = (1/f)
II. Lens formula : (1/v) + (1/u) = (1/f)
- A beam of parallel light, originating from a distant source, is first incident on a convex lens with focal length $f_2$.
Subsequently, the light passes through the lens and then reflects from a concave mirror having a focal length $f_1$.
The concave mirror is placed at a distance $d$ from the convex lens.
For the light rays to retrace their original path and ultimately emerge from the lens as a parallel beam heading back towards the distant source, the separation distance $d$ between the lens and the mirror must be: The focal length of a mirror is f. If it is placed in water (n = 4/3), its focal length will be:
