Page 5 - 10-phy-12 Geometrical Optics
P. 5
Experiment Find the refractive index of water by
using a concave mirror.
12.2
Date ________________
If the object is placed at the centre of curvature of a concave mirror, the
Background incident ray will be normal to the mirror and will be reflected back along the
Information same path. The image will be formed at the same position as that of object. This
image will be real, inverted and equal in size.
In Fig. 12.2.1, an object is placed at point A which is the centre of
curvature of the concave mirror. The ray ABC strikes the surface of the mirror at
C normally. This ray reflects back along the same path. The image is formed at A.
There will be no parallax between the object and image atA.
On pouring some water on the surface of the mirror, the previous position
of the image is changed and a parallax occurs. In order to remove this parallax the
object has to be moved down to another position D.
Now the ray DB strikes the surface of water making an angle of incidence
i = NBD. It refracts into water and bends towards the normal along BC. As it
strikes at C normally, so retraces its path and the image is formed at D.
A
N D h1
i h2
r
BO
i
CF E
Fig. 12.2.1
7
using a concave mirror.
12.2
Date ________________
If the object is placed at the centre of curvature of a concave mirror, the
Background incident ray will be normal to the mirror and will be reflected back along the
Information same path. The image will be formed at the same position as that of object. This
image will be real, inverted and equal in size.
In Fig. 12.2.1, an object is placed at point A which is the centre of
curvature of the concave mirror. The ray ABC strikes the surface of the mirror at
C normally. This ray reflects back along the same path. The image is formed at A.
There will be no parallax between the object and image atA.
On pouring some water on the surface of the mirror, the previous position
of the image is changed and a parallax occurs. In order to remove this parallax the
object has to be moved down to another position D.
Now the ray DB strikes the surface of water making an angle of incidence
i = NBD. It refracts into water and bends towards the normal along BC. As it
strikes at C normally, so retraces its path and the image is formed at D.
A
N D h1
i h2
r
BO
i
CF E
Fig. 12.2.1
7
