A person has a far point of 50 cm. If he is wearing glasses 2 cm from the eyes, determine the power of the lens needed for him to see distant object clearly.​

The power will be "2.08 D".

Explanation:

According to the question,

The location of the image form lens,

We know that,

⇒

here,

= Object location

= Image location

= Focal length

On putting the values in the above expression, we get

⇒

or,

hence,

The refractive power will be:

⇒

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.