Question

Doctor advised to use 3D lens.what is its focal length​

Answer 1

Answer:

1/f=1/v-1/u this is right answer of 3d lens focal length

Explanation:

Thank you :Ratnala yugandar

Answer 2

Answer:

The focal length of the lens is 0.33m or 33 cm

Explanation:

Here we have been given that the doctor has prescribed the patient to use the lens with a power of + 3 D or the 3D lens.

Here 3 D lens means the lens with a power of 3 dioptre(D)

Now we can find the focal length of the lens as below:

$P = \frac{1}{f}$

where P is the power and f is the given focal length of the respective lens.

∴ 3 = $\frac{1}{f}$

⇒ $f = \frac{1}{3}$

⇒ f = 0.33 m

We know  1m = 100cm,

⇒ f = 33 cm                      

Therefore the focal length of the lens is 0.33m or 33 cm.