SCERT Maharashtra solutions for सायन्स अँड टेक्नॉलॉजी पार्ट १ [इंग्रजी] इयत्ता १० महाराष्ट्र राज्य मंडळ chapter 7 - Lenses [Latest edition]

A ray of light gets refracted ______ while entering the lens.

The point inside the lens on the principal axis through which light rays pass without changing their path is called _______.

Virtual image is formed by a convex lens if an object is placed _______.

In the convex lens if an object is placed at 2 F₁, the image is formed at ______.

All distances parallel to the principal axis are measured from the _______.

A small hole of changing diameter at the centre of Iris is called _______.

For a normal human eye the near point is at _______.

The image formed by _______ lens is always virtual and small.

In a relaxed state, the focal length of healthy eyes is _______.

For a specific glass lens f = 0.5 m. This is the only information given to the student. Which type of lens is given to him and what is its power?

In Myopia the human eye _______.

Due to elongation of _______ and increase in curvature of the eye lens, a person cannot see distant objects clearly.

In hypermetropia human eye _______.

Bifocal lens is required to correct _______ defect.

_______ times larger images can be obtained by using a simple microscope.

_______ is a combination of two convex lenses with small focal length.

Convex lens : converging : : concave lens : _______

Nearsightedness: elongated eyeball : : farsightedness: _______

Object at 2F₁ of a convex lens : Image at 2F₂ : : Object at F₁ : _______

Nearsightedness : concave lens : : farsightedness : _______

Simple microscope : Number of convex lens one : : compound microscope : _______

Focal length : metre : : power of lens : _______

: Concave lens : : : ______

: Object near the lens : : ______ :

Find the odd one out and give its explanation.

Find the odd one out and give its explanation.

Find the odd one out and give its explanation.

Find the odd one out and give its explanation.

Find the odd one out and give its explanation.

Write the name.

The distance between focus and optical centre.

Write the name.

The part of human eye that transmits electrical signals to the brain.

Write the name.

The lens used in simple microscope.

Name the capacity of the eye lens to change its focal length as per need.

Write the name.

The defect of eye occurring due to ageing

Write the name.

The fleshy screen behind cornea.

Write the name.

The screen with light sensitive cells in human eye.

Write the name.

The sensation on the retina persists for a while is

Write the name.

The persons which are unable to distinguish between different colours

Write the name.

The imaginary line passing through two optical centres of lens

Convex magnifying glass is called divergent magnifying glass and concave magnifying glass is called converging magnifying glass.

The image of the object in the human eye is formed on the cross screen.

Hypermetropia can be corrected using concave lens of proper focal length.

When the incident ray is parallel to the principal axis, the refracted ray passes through the principal focus.

The image of an object at an infinite distance is obtained in a real and erect form through a convex magnifying glass.

The power of the magnifying glass depends on the distance of the magnifying glass from object.

The lens of the eye is flattened when looking at nearby objects.

For a healthy human eye, the distant point is infinite distance.

Vision defect that increases distance between the lens of the eye and retina of the eye is termed as myopia.

The virtual image of object seen by the eye depends on the angle subtended by the object with the eye.

Write an Explanation.

Centre of curvature of the lens

Write an Explanation.

The optical centre of the lens

Write an Explanation.

Principal focus

Write an Explanation.

Focal length

Write an Explanation.

Principal axis

Write an Explanation.

Minimum distance of distinct vision.

Write an Explanation.

Farthest distance of distinct vision

Write an Explanation.

Magnification

Write an Explanation.

Power of accommodation

Write an Explanation.

Persistence of vision

Write scientific reason.

A convex lens is called a converging lens.

Write scientific reason.

Nearsightedness, this defect can be corrected by using spectacles with concave lens.

Write scientific reason.

Farsightedness, this defect can be corrected by using convex lens.

Write scientific reason.

Adults need bifocal lens spectacle.

Write scientific reason.

Presbyopia effect is more common in people over 40 years of age.

Give a scientific reason.

Simple microscope is used for watch repairs.

Give scientific reason:
One can sense colours only in bright light.

Write scientific reason.

The movie cannot be enjoyed if seat of a viewer is too close to the screen in the cinema.

Give scientific reason:

We cannot clearly see an object kept at a distance less than 25 cm from the eye.

Distinguish between:

Concave lens and Convex lens

Distinguish between:

Farsightedness and Nearsightedness.

Distinguish between:

Myopia - Presbyopia

Find the power of a convex lens of focal length of + 25 cm.

If focal length of a convex lens is 20 cm at what is the power of the lens?

If each two concave lenses of focal length 30 cm are kept in contact with each other what will be the power of combination?

An object is placed at a distance of 10 cm from a convex lens of focal length 12 cm, find out at what distance image will be formed from the lens and what is the nature of image.

5 cm high object is placed at a distance of 10 cm from a converging lens of focal length of 20 cm. Determine the position, size and type of the image.

An object is placed vertically at a distance of 20 cm from a convex lens. If the height of the object is 5 cm and the focal length of the lens is 10 cm, what will be the position, size and nature of the image? How much bigger as compared to the object?

Two convex lenses of focal length 30 cm and 10 cm each are kept in contact with each other. Find the power of their combination.

The following figure show the change in the shape of the lens while seeing distant and nearby objects. Complete the figures by correctly labelling the diagram.

The following figure show the change in the shape of the lens while seeing distant and nearby objects. Complete the figures by correctly labelling the diagram.

Write the function of the human eye and label parts of the figure given below.

Observe the given below the figure, correct it and explain and write about the concept depicted in this figure.

Given below is a diagram showing a defect of vision. Name the defect of vision and draw an accurately labelled diagram to correct this defect.

Write law in a given figure.

Write law in a given figure.

Write law in a given figure.

Observe the given figure and answer the following questions.

1. Where is the above type of lens construction used?
2. What type of image is formed by an objective lens?
3. What happens instead of placing at F_o if the object is placed in between O and F_o?

Identify and explain concepts given in this diagram.

Complete the paragraph by choosing the right options given below.

(minimum, near point, 25 cm, farthest, farthest distance, far point)

The _______ distance of an object from a normal eye, at which it is clearly visible without stress on the eye, is called the minimum distance of distinct vision. The position of the object at this distance is called the _______ of the eye, for a normal human eye, the near point is at _______. The _______ distance of an object from a human eye, at which it is clearly visible without stress on the eye is called _______ of distinct vision. The position of the object at this distance is called the _______ of the eye.

Choose the correct option from the bracket and complete the stanza.

(colour blind, actual, conical, light-sensitive, rodlike, colours)

The retina in our eyes is made up of many _______ cells. These cells are shaped like a rod and like a cone. The _______ cells respond to the intensity of light and give information about the brightness or dimness of the object to the brain. The _______ cells respond to the colour and give information about the colour of the object to the brain. Brain processes all the information received and we see the _______ image of the object. Rod like cells respond to the faint light also but ______ cells do not. Some people lack conical cells responding to certain colours. These persons cannot recognize those colours or cannot distinguish between different ______. These persons are said to be ______.

Explain with a ray diagram the position, size, and nature of the various image formed by convex lenses.

An object is at infinity.

Explain with a ray diagram the position, size, and nature of the various images formed by the convex lens.

An object beyond 2F₁.

Explain with a ray diagram the position, size, and nature of the various images formed by a convex lens.

An object at 2F₁.

Explain with a ray diagram the position, size, and nature of the various images formed by a convex lens.

An object is in between F₁ and 2F₁

Explain with a ray diagram the position, size, and nature of the various images formed by a convex lens.

Object at focus F₁

Explain with a ray diagram the position, size, and nature of the various images formed by a convex lens.

Object between F₁ and O