Medium
$(i)$ Describe an activity to find the approximate value of the focal length of a concave mirror.
$(ii)$ What happens to the size of the image of an object when it is moved gradually away from a convex mirror?
$(iii)$ In an experiment to study refraction through a glass slab,it is observed that a ray of light undergoing refraction emerges parallel to the direction of the incident ray. Why does it happen so? Explain with the help of a diagram.
$(ii)$ What happens to the size of the image of an object when it is moved gradually away from a convex mirror?
$(iii)$ In an experiment to study refraction through a glass slab,it is observed that a ray of light undergoing refraction emerges parallel to the direction of the incident ray. Why does it happen so? Explain with the help of a diagram.
(N/A) $(i)$ Activity: Hold a concave mirror in your hand and direct it towards a distant object (like a window or a tree). Direct the light reflected by the mirror onto a sheet of paper held close to the mirror. Move the sheet back and forth slowly until a bright,sharp spot of light is seen on the paper. The distance of this image from the position of the mirror gives the approximate value of the focal length of the mirror.
$(ii)$ As an object is moved gradually away from a convex mirror,the size of the image becomes smaller and it shifts towards the focus.
$(iii)$ When a light ray passes through a rectangular glass slab,it undergoes refraction at two parallel surfaces,$PQ$ (air-glass interface) and $SR$ (glass-air interface). The extent of bending of the ray of light at the first surface is equal and opposite to the bending at the second surface. Thus,the emergent ray is parallel to the incident ray,but it is laterally displaced. This is shown in the diagram below.
$(ii)$ As an object is moved gradually away from a convex mirror,the size of the image becomes smaller and it shifts towards the focus.
$(iii)$ When a light ray passes through a rectangular glass slab,it undergoes refraction at two parallel surfaces,$PQ$ (air-glass interface) and $SR$ (glass-air interface). The extent of bending of the ray of light at the first surface is equal and opposite to the bending at the second surface. Thus,the emergent ray is parallel to the incident ray,but it is laterally displaced. This is shown in the diagram below.
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Similar Questions
Which of the following statements is true for light waves?
Easy
View SolutionDraw ray diagrams showing the image formation by a convex lens when an object is placed:
$(a)$ Between optical centre and focus of the lens.
$(b)$ Between focus and twice the focal length of the lens.
$(c)$ At twice the focal length of the lens.
$(d)$ At infinity.
$(e)$ At the focus of the lens.
$(a)$ Between optical centre and focus of the lens.
$(b)$ Between focus and twice the focal length of the lens.
$(c)$ At twice the focal length of the lens.
$(d)$ At infinity.
$(e)$ At the focus of the lens.
Medium
View Solution$(i)$ Define the principal focus of a concave mirror.
$(ii)$ Why do we prefer a convex mirror as a rear-view mirror in vehicles?
$(iii)$ We wish to obtain an erect image of an object using a convex lens. Draw a ray diagram to show the image formation in this case.
$(ii)$ Why do we prefer a convex mirror as a rear-view mirror in vehicles?
$(iii)$ We wish to obtain an erect image of an object using a convex lens. Draw a ray diagram to show the image formation in this case.
Medium
View SolutionStudy the given ray diagrams and select the correct statement from the following:
$(A)$ Device $X$ is a concave mirror and device $Y$ is a convex lens, whose focal lengths are $20 \text{ cm}$ and $25 \text{ cm}$ respectively.
$(B)$ Device $X$ is a convex lens and device $Y$ is a concave mirror, whose focal lengths are $10 \text{ cm}$ and $25 \text{ cm}$ respectively.
$(C)$ Device $X$ is a concave lens and device $Y$ is a convex mirror, whose focal lengths are $20 \text{ cm}$ and $25 \text{ cm}$ respectively.
$(D)$ Device $X$ is a convex lens and device $Y$ is a concave mirror, whose focal lengths are $20 \text{ cm}$ and $25 \text{ cm}$ respectively.
$(A)$ Device $X$ is a concave mirror and device $Y$ is a convex lens, whose focal lengths are $20 \text{ cm}$ and $25 \text{ cm}$ respectively.
$(B)$ Device $X$ is a convex lens and device $Y$ is a concave mirror, whose focal lengths are $10 \text{ cm}$ and $25 \text{ cm}$ respectively.
$(C)$ Device $X$ is a concave lens and device $Y$ is a convex mirror, whose focal lengths are $20 \text{ cm}$ and $25 \text{ cm}$ respectively.
$(D)$ Device $X$ is a convex lens and device $Y$ is a concave mirror, whose focal lengths are $20 \text{ cm}$ and $25 \text{ cm}$ respectively.
MediumCBSE 2017
View SolutionState one practical use of each of the following: $(i)$ convex mirror, (ii) concave mirror, (iii) convex lens, and (iv) concave lens.
Medium
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