Question

Define the term Power of Accommodation. Write the modification in the curvature of the eye lens, which enables us to see the nearby object clearly. Give relation between power and focal length.​

Answer 1

**Power of Accommodation:** The power of accommodation, also known as the accommodation reflex, refers to the eye's ability to adjust its focus from distant objects to near objects by changing the shape of the eye's crystalline lens. This adjustment allows us to see objects clearly at various distances.

**Modification in the Curvature of the Eye Lens for Near Vision:**

When we look at nearby objects, the ciliary muscles surrounding the eye's lens contract. This contraction causes the suspensory ligaments to slacken, which in turn allows the elastic and flexible crystalline lens to become more rounded or bulged. This increased curvature of the lens increases its refractive power, enabling it to bend incoming light rays more sharply. As a result, the image of the nearby object is focused directly onto the retina, allowing us to see it clearly.

**Relation Between Power and Focal Length:**

The power (P) of a lens is inversely proportional to its focal length (F) and is measured in diopters (D). The formula that relates power and focal length for a lens is as follows:

\[P = \frac{1}{F}\]

Where:

- \(P\) is the power of the lens in diopters (D).

- \(F\) is the focal length of the lens in meters (m).

In this formula, a lens with a shorter focal length has more power (measured in diopters), meaning it can bend light more strongly and is suitable for bringing nearby objects into focus. Conversely, a lens with a longer focal length has less power and is better suited for focusing on distant objects.

The ability of the eye's lens to adjust its curvature (and therefore its power) is crucial for maintaining clear vision at various distances, a process known as accommodation.

Step-by-step explanation:

Answer 2

The Power of Accommodation :- the ability of the eye's lens to adjust its curvature in order to focus on objects at varying distances. This adjustment enables clear vision for both nearby and distant objects by changing the lens's focal length.

The modification in the curvature of the eye lens that allows us to see nearby objects clearly is known as accommodation.

✫ When we focus on a nearby object, the ciliary muscles contract, causing the lens to become thicker and more curved, which increases its refractive power.

The relation between power (P) and focal length (f) of a lens is given by the formula: m
`\pmb{ \sf{P = (1)/(f)}}`

where:

• P is the power of the lens measured in diopters
• f is the focal length of the lens measured in meters

When the lens in our eye gets curvier and more powerful, its focal length becomes shorter. This helps us see things up close by adjusting our focus.