एक सामान्य मानव आँख द्वारा किसी वस्तु को स्पष्ट रूप से देखने के लिए, प्रकाश किरणों को कहाँ पर केंद्रित होना चाहिए?

A person can clearly see objects only at distances greater than 40 cm. Assuming the near point of a normal eye is 25 cm, what power of corrective lens should he be advised to use?

The power of accommodation of the human eye refers to the ability of the eye to: