Q: Hypermetropia is a synonym for:

Hypermetropia is also known as far-sightedness. A person with hypermetropia can see distant objects clearly but cannot see nearby objects distinctly.Myopia is also known as near-sightedness. A person with myopia can see nearby objects clearly but cannot see distant objects distinctly.The power of accommodation of the eye usually decreases with aging.

Q: A convex glass lens is immersed in water. Compared to the power in air, its power in water will :

Power of a lens \$=\dfrac{1}{f}\$Where \$f \$ is the focal length of the lens.So, by lens maker formula\$\dfrac{1}{f}=\left ( \dfrac{\mu _{2}}{\mu _{1}}-1 \right )\left ( \dfrac{1}{R_{1}}-\dfrac{1}{R_{2}} \right )\$As lens is dipped in water, \$\mu\$ of the medium is increased from 1 to \$\dfrac{4}{3} \$ (i.e. refractive index of water), so, \$\dfrac{\mu_{2}}{\mu_{1}}\$ term decreases, so, \$\left ( \dfrac{\mu_{2}}{\mu_{1}}-1 \right )\$ term decrease which leads to decrease of \$\dfrac{1}{f}.\$ so, power \$\left ( =\dfrac{1}{f} \right )\$ decreases.

Question 1

In an astronomical telescope the focal lengths of objective and eyepiece should respectively be :

Accepted Answer

In an astronomical telescope, two convex lenses are used for different focal lengths. In which the lens with large focal length is an objective lens which is used to see large distance objects like stars or planets and the one with small focal is eyepiece. Hence correct option is A.

Question 2

The image formed by the telescope in normal adjustment position is at :

Accepted Answer

The image formed by the telescope in normal adjustment position is at infinity, so, that we can look at distant objects such as a star, a planet etc. Hence option D is correct.

Question 3

A myopic person cannot see distinctly , objects that are :

Accepted Answer

Myopia is a vision defect in which a person can see nearby objects clearly but is not able to see distinct objects clearly. In this defect, the rays coming from distant objects, focus in front of retina, instead of on retina.

Question 4

Myopia occurs due to:

Accepted Answer

Myopia is the term used to define short sightedness.  Light from a distant object forms an image before it reaches the retina.  This is because the eye ball is too large, or the cornea or crystalline lens is too strong.  This results in decrease in focal length of eye lens, whereas the distance between retina and lens is always constant.

Question 5

The optical instrument with zero power is :

Accepted Answer

A telescope has a larger value of its focal length. we know that Power $P = \dfrac{1}{f}$ so because telescope has a larger focal length so it's power which is inversely related to its focal length is approximately equal to zero.Thus the optical instrument with zero power is telescope because it is a system with large focal length.

Question 6

For a myopic (short-sighted) eye, rays from far distant objects are brought to focus at a point:

Accepted Answer

In a myopic eye, rays from distant objects are brought to focus at a point in between eye lens and retina. A myopic person can not see distance objects clearly, but is able to see nearby objects clearly.

Question 7

Inability of the eye to focus on both far and near objects with advancing age is:

Accepted Answer

With advancing age when ciliary muscles become weak and are not able to strain enough to reduce focal length to appropriate value then this defect is known as presbyopia.

Question 8

Hypermetropia is a synonym for:

Accepted Answer

Hypermetropia is also known as far-sightedness. A&#10;person with hypermetropia can see distant objects&#10;clearly but cannot see nearby objects distinctly.Myopia is also known as near-sightedness. A person with myopia&#10;can see nearby objects clearly but&#10;cannot see distant objects distinctly.The power of accommodation of the eye usually&#10;decreases with aging.

Question 9

In the case of hypermetropia:

Accepted Answer

In hypermetropia image of a distance object is formed on the retina and image of a near object is formed behind the retina. For correction of hypermetropia , convex lens is used.

Question 10

A convex glass lens is immersed in water. Compared to the power in air, its power in water will :

Accepted Answer

Power of a lens $=\dfrac{1}{f}$Where $f $ is the focal length of the lens.So, by lens maker formula$\dfrac{1}{f}=\left ( \dfrac{\mu _{2}}{\mu _{1}}-1 \right )\left ( \dfrac{1}{R_{1}}-\dfrac{1}{R_{2}} \right )$As lens is dipped in water, $\mu$ of the medium is increased from 1 to $\dfrac{4}{3} $ (i.e. refractive index of water), so, $\dfrac{\mu_{2}}{\mu_{1}}$ term decreases, so, $\left ( \dfrac{\mu_{2}}{\mu_{1}}-1 \right )$ term decrease which leads to decrease of $\dfrac{1}{f}.$ so, power $\left ( =\dfrac{1}{f} \right )$ decreases.

Ray Optics And Optical Instruments

Physics
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In an astronomical telescope the focal lengths of objective and eyepiece should respectively be :

The image formed by the telescope in normal adjustment position is at :

A myopic person cannot see distinctly , objects that are :

Myopia occurs due to:

The optical instrument with zero power is :

For a myopic (short-sighted) eye, rays from far distant objects are brought to focus at a point:

Inability of the eye to focus on both far and near objects with advancing age is:

Hypermetropia is a synonym for:

In the case of hypermetropia:

A convex glass lens is immersed in water. Compared to the power in air, its power in water will :

Ray Optics And Optical Instruments

Physics 4649 Views

In an astronomical telescope the focal lengths of objective and eyepiece should respectively be :

The image formed by the telescope in normal adjustment position is at :

A myopic person cannot see distinctly , objects that are :

Myopia occurs due to:

The optical instrument with zero power is :

For a myopic (short-sighted) eye, rays from far distant objects are brought to focus at a point:

Inability of the eye to focus on both far and near objects with advancing age is:

Hypermetropia is a synonym for:

In the case of hypermetropia:

A convex glass lens is immersed in water. Compared to the power in air, its power in water will :

Physics
4649 Views