Explanation
Correct answer is (c)
The angle formed between the normal and refracted ray at the point of refraction is called angle of refraction.
Correct answer is (B)
Iris is a thin diaphragm composed mostly of connective tissue and smooth muscle fibers which is visible through the clear cornea as the colored disc inside of the eye. It is situated between the cornea and the crystalline lens.
Correct answer is (D)
Iris is the ring of pigmented tissue surrounding the pupil that varies in color from person to person, it contract and dilates to control the amount of light entering the eye through the pupil. The pupil is the opening in the center of the iris where light enters the eye.
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.
Correct answer ( B )
The circular aperture through which light enters the eye is known as the pupil. It is the black circle in the center of the iris when the light reaches the tissues at the back of the eye, it is absorbed making the pupil look black. The pupil controls the amount of light that enters the eye.
$$\textbf{Step 1-Image formation for convex lens}$$
Convex lens forms virtual, erect and magnified image if object is placed between the mirror and its focal length.
$$\textbf{Step 2-Power of lens}$$
As focal length of lens decreases, power will increase as it is inversely related to each other. So, for smaller focal length image would be very large.
Here, convex lens with smallest focal length is 5 cm.
$$Answer:$$
Hence, option C is the correct answer.
Correct answer is (c).
Long-sightedness, affects a person's ability to see objects close to them, these vision problems are also referred to as refractive errors. A person having long-sighted eye, usually is able to see distant objects clearly, but nearby objects will be out of focus, and as the man cannot see the objects distinctly at a distance less than 1 meter so he is suffering from Long-sightedness.
If a person cannot see an object clearly when it is placed at about 25 cm away from him, he is suffering from:
Correct answer (a)
The power of accommodation of the eye usually decreases with ageing. For most people, the near point gradually recedes away. They find it difficult to see nearby objects comfortably and distinctly without corrective eye-glasses. This defect is called Presbyopia. It arises due to the gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens.
Sometimes, a person may suffer from both myopia and hypermetropia. Such people often require bi-focal lenses. The upper portion consists of a concave lens. It facilitates distant vision. The lower part is a convex lens. It facilitates near vision.
The blue colour of the sky is due to the scattering of light by small particles of the atmosphere (air molecules). When white light (from the sun) enters the earth's atmosphere, it gets scattered away due to the atmospheric particles. Since blue colour has the minimum wavelength, so blue colour scatters the most and thus the sky appears blue.
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