Physics

Optics and Lenses

206 Questions

Enhance your physics knowledge by practicing questions on optics and the functioning of lenses. The set covers calculating combined focal lengths, lens power, and correcting vision defects like myopia and hypermetropia. These physics fundamentals are crucial for medical entrance and state board exams.

Combined focal lengthCorrecting vision defectsLens power calculationConvex and concave lensesTelescopesHuygens principle

Optics and Lenses Questions

Multiple choice physics the human eye and the colourful world human eye and its working what is inside our eyes? human eye and defects of vision

What kind of lens is there in our eyes? 

  1. concave

  2. convex

  3. Plano-concave

  4. Plano-convex
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is B.
Our eye lenses are convex lenses with variable focal lengths. The focal length of the eye lens is controlled by muscles according to the distance of the object from us that we are trying to see. The lens is flexible and when it is acted on by the ciliary muscle around it, the lens can be "flattened" to change the focus, or, when the muscle is relaxed, the lens can be assumed as having a more spherical shape. This is the principle of the eye to focus on objects nearer or farther away.

Multiple choice evs we are special defects of eye disorders of nervous system braille script

Concave lens is used to correct 

  1. Myopia

  2. Presbiopia

  3. Hypermetropia

  4. Cataract
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Myopia is nearsightedness and short-sightedness, is a condition of the eye where the light that comes in does not directly focus on the retina but in front of it, causing the image that one sees when looking at a distant object to be out of focus, but in focus when looking at a close object.
It can be corrected by the use of corrective lenses that have a negative optical power i.e., concave glasses which compensates for the excessive positive diopters of the myopic eye.
So, the correct answer is option A.

Multiple choice evs we are special defects of eye disorders of nervous system braille script

Concave lens is employed to correct _______.

  1. Presbyopia

  2. Hypermetropia

  3. Cataract

  4. Myopia
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A. Presbyopia occurs in the late age (generally after 40 years) due to loss of elasticity of eye lens due to which nearby objects are not correctly visible. It is corrected by using bifocal lengths.
B. Hypermetropia occurs when eye ball becomes shorter and it results in the formation of image behind the retina. It is corrected using convex lens which focus the light rays on the retina.
C. Cataract is an eye disease that occurs in older people. The visibility is reduced because the eye lens becomes opaque. It is treated by surgery.
D. Myopia occurs when eye ball becomes longer and it results in the formation of image in front of retina. It is corrected using concave lens which diverge the light rays to get focussed on the retina. 
So, the correct answer is 'Myopia'.
Multiple choice evs we are special defects of eye disorders of nervous system braille script

Convex lenses correct

  1. Presbyopia

  2. Myopia

  3. Hypermetropia

  4. Glaucoma
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
A. Presbyopia occurs in the late age (generally after 40 years) due to loss of elasticity of eye lens due to which nearby objects are not correctly visible. It is corrected by using bifocal lengths.
B. Myopia occurs when eye ball becomes longer and it results in the formation of image in front of retina. It is corrected using concave lens which diverge the light rays to get focussed on the retina. 
C. Hypermetropia occurs when eye ball becomes shorter and it results in the formation of image behind the retina. It is corrected using convex lens which focus the light rays on the retina.
D. Glaucoma is a disorder of eye in which the optic nerve which carries visual information to brain, is damaged and this leads to blindness.
So, the correct answer is 'Hypermetropia'.
Multiple choice evs we are special defects of eye disorders of nervous system braille script

Convex lens is used to correct 

  1. Hypermetropia

  2. Myopia

  3. Cataract

  4. Glaucoma
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hypermetropia occurs when the light is focused behind the retina. So, the lens changes its thickness, which aims to bring the light into focus on the retina - a process is called as accommodation. But, people with long sight cannot accommodate fully and so the light does not focus sharply and vision is blurred. This occurs because either the eyeball is too short, the cornea is too flat or the lens cannot become round enough. The simplest, cheapest and safest way to correct long-sightedness is with glasses. 

Convex prescription lenses (called as plus lenses) are used to bend light rays slightly inwards. The light rays then have a lesser angle to bend back to focus, when travelling through the cornea and lens. As a result, the light rays focus further forward on the retina. 

Multiple choice evs we are special defects of eye disorders of nervous system braille script

To correct myopia, one should use 

  1. Convex lens

  2. Concave lens

  3. Plane lens

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Myopia also known as nearsightedness or short-sightedness is a condition of the eye where light focuses in front, instead of on the retina. People having myopia can see close objects clearly, but objects farther away appear blurred. It occurs if the eyeball is too long or the cornea is too curved. So, the correct answer is option B.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Lenses used in ultraviolet microscope are

  1. Glass lenses.

  2. Quartz fluorite.

  3. Lithium fluoride.

  4. Both B and C.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Standard glass lenses absorb ultraviolet light, making them unsuitable for UV microscopy. Quartz and fluorite are transparent to UV radiation, so lenses made from these materials are used instead.

Multiple choice

Type of lens to correct for myopia

  1. Diverging

  2. Convex

  3. Converging

  4. Magnifying
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Myopia (nearsightedness) is corrected with a diverging (concave) lens, which spreads out the light rays before they reach the eye to compensate for the eye's tendency to focus light too far in front of the retina.

Multiple choice physics wave optics resolving power of optical instruments resolution of optical instruments diffraction

High quality lens system for optical instrument is made by using ..............

  1. Concave and convex lens

  2. Convex lens

  3. Concave lens

  4. Concave and convex mirror
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

High-quality optical systems use combinations of concave and convex lenses (achromatic doublets) to correct for chromatic and spherical aberrations.

Multiple choice physics observing space: telescopes space research and satellites space travel space exploration and forms of light

Which of the following is correct about astronomical telescope?

  1. It consists of two diverging lenses

  2. Its objective is a concave lens

  3. Its eyepiece is a convex lens with greater focal length than the objective

  4. The final image in this telescope is inverted
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Since in astronomical telescopes we are not much bothered about the inverted carterer. So, we get final image in this telescope is inverted where in terrestrial, we get upright image.

Multiple choice physics observing space: telescopes space research and satellites space travel space exploration and forms of light

State whether true or false :

Both the telescope and compound microscope make use of two lenses-one concave and one convex.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Both the telescope and compound microscope make use of two lenses–one concave and one convex. [a] false

Both the lenses are convex lenses

The main difference between telescope and microscope is that microscopes are used to magnify small objects that are at a short distance from the viewer whereas telescopes are used to magnify large objects that are at a large distance from the viewer. In refracting telescopes, there are typically two convex lenses. One lens acts as the objective lens: this lens gathers light from faraway objects and forms a real, inverted image of the object at its focal point. A second lens, called the eyepiece

Microscopes are used to look at magnified images of small objects. A simple microscope consists of a single convex lens. The lens is held close to the object so that the object is between the lens and its focal point.