NCERT Retina Science Chapter Class 10
Retina is present in the rear part of eye ball.
It is a delicate membrane which acts as a light sensitive screen.
It has a large number of light sensitive cells named rods and cones.
Q : Difference between rods and cones ?
Rods:
They are rod shaped.
They help for intensity of light.
Cones :
They are cone shaped.
They help for colour of vision.
Optic Nerve
The transmit electrical signal to the brain.
Accommodation
It is the ability of the human eye to focus the near by as well as distance objects by adjusting the focal length with the help of cilliary muscles is known as accommodation.When you are looking near by object
U= -25cm
V=2.5cm
1/f=1/v-1/u
=1/2.5-1/-25
=10/25+1/25
=11/25
F=25/11
P=100/25*14
=44D
When you are looking at distant objects
u = -
v = 2.5
1/f = 1/v-1/u
=1/2.5-1/
=1/2.5=2/5
F = 5/2 cm
P = 100/5*2cm
40 D
Power of accommodation
44D – 40D = 4D
