E XERCISES
1. Which one of the following materials cannot be used to make a lens?
(a) Water
(b)
Glass
(c) Plastic (d) Clay
2. The image formed by a concave mirror is observed to be virtual, erect and larger
than the object. Where should be the position of the object?
(a) Between the principal focus and the centre of curvature
(b) At the centre of curvature
(c) Beyond the centre of curvature
(d) Between the pole of the mirror and its principal focus.
3. Where should an object be placed in front of a convex lens to get a real image of the
size of the object?
(a) At the principal focus of the lens
(b) At twice the focal length
(c)
At infinity
(d) Between the optical centre of the lens and its principal focus.
4. A spherical mirror and a thin spherical lens have each a focal length of -15 cm. The
mirror and the lens are likely to be
(a) both concave.
(b) both convex.
Light - Reflection and Refraction
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Answers
1)Glass and water are transparent materials. There is a certain amount of plastic that is transparent so that the plastic can be used to make a lens, but the clay is an opaque substance so that the light can not be transmitted into it and the clay can not be used to create the lens
2)Answer. (d) Between the pole of the mirror and its principal focus. A concave mirror forms a virtual and erect image only when the object is placed between the poles of the mirror and it's principal focus. This image is larger than the size of object, ie, it is magnified.
Explanation:
3) ) At twice the focal length,If an object is placed in front of convex lens at twice of the focal length then the image will be real. the size of image will be same of size of object
4)
Answer:
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