A metal disc radius 50cm rotates at 20 revolutions per seconds about it's axis which is parallel to a uniform magnetic field of 0.3T.
i What is the area swept out by any radius of the disc in one revolution?
ii. What is the flux Cut by the radius in one revolution?
iii. what is the induced EMF between the centre
of the disc and the rim?

a electromagnetic waves

answer: the correct answer for the fill in the blank is rods.

rods are the specialized photoreceptor cells that are present in the retina of human eye. they are responsible for vision in the night time ( also called scotopic vision). they have very low visual acuity and color distinguishing ability.

as they are responsible for vision in night time, therefore they are found predominantly in the nocturnal animals.