Education

 CBSE-Light Accommodation of the eye The ability of the eye to focus on near and distant objects, by adjusting its focal length, is called the accommodation of the eye.

CBSE notes-Light Principal focus of concave and convex mirror. :Principal focus of a concave mirror (i) The principal focus of a concave mirror is a point on its principal axis to which all the light rays, which are parallel and close to the axis, converge after reflection from the concave mirror. (ii) A concave mirror has real focus. Principal focus of a convex mirror (i) The principal focus of a convex mirror is a point on its principal axis from which a beam of light rays, initially parallel to the axis, appear to diverge after being reflected from the convex mirror.

CBSE notes-Light What is the nature, size and position of the image formed of an object at infinity? Explain how it is used as a doctor’s mirror. Solution:When an object is placed at infinity from a concave mirror, the image formed is (i) real and inverted   (ii) highly diminished and   (iii) at the focus When the object is at infinity, the image is formed at the focus of the concave mirror, hence the mirror can concentrate all the parallel rays of the light to its focus. This explains the use of concave mirror as a doctor’s head-mirror. A concave mirror is used as a head-mirror by the doctors to concentrate light on the body parts to be examined.  

CBSE notes-Light Define the principal focus of a concave mirror. Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.