Question

the power of a lens is -2D ..then what is its focal length?

Answer 1

As we know p=1/f
So here p= -2
So ,
-2= 100(in cm)/f
Now, f=100/-2
=-50.
Therefore focal length of the lens is -50

Answer 2

The focal length of the power of a lens is -2D is

Explanation:

• We know while making a lens for correcting a defect in the eye the first thing, we need to know is the focal length of the lens.
• And so that length can be corrected using the lens accordingly.
• Eye lenses power is found out using the focal length that we get out of lens formula or we can also say it is the reciprocal of the focal length we get now as in this question we are given the power of the lens.

• Thee focal length can be found and it would be reciprocal of this power $\frac{1}{2} = -0.5m$

To know more:

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