Page 2 - X-CBQ-Worksheet-LIGHT

d) The focal length on one side of the lens is smaller than that on the other.
8. Solar cookers contain a concave mirror. How does the concave mirror help in 1
heating the food? State whether the following responses are true or false:
a) Sun’s rays are absorbed by the mirror.
b) Sun’s rays relected by the mirror converge at a point.
c) Sun’s rays diverge out when reflected by the mirror.
9. The power of a lens (P) is calculated by the formula, 2
P = 1/f
where f is the focal length of the lens.
A lens has a focal length of – 0.25 m. Is it a convex lens or a concave lens?
Explain your answer.
10. Rekha placed a juice bottle at a distance of 20 cm in front of a convex mirror 2
which has a focal length of 20 cm. Where is the image likely to form?
11. A student conducts an activity using a flask of height 15 cm and a concave 2
mirror. He finds that the image formed is 45 cm in height. What is the
magnification of the image?
12. Rahul conducts an experiment using an object of height 10 cm and a 3
concave lens with focal length 20 cm. The object is placed at a distance of 25
cm from the lens. Can the image be formed on a screen? What is the
location of the image if it can be formed?
13. A student conducts an experiment using a convex lens. He places the object 3
at a distance of 60 cm in front of the lens and observed that the image is
formed at a distance of 30 cm behind the lens. What is the power of the
lens?
14. Neeti took some clear gel beads and soaked them 3
in water for a few hours. The gel beads absorbed
water and increased in size. She then placed
these beads in a glass container. The beads were
clearly visible in the container as shown below.
Neeti then added water to the container and it
appeared as shown below.
a) Why are the gel beads not visible on adding
water?
b) Would the gel beads shown in the first image
be visible if placed in oil instead of water? Give a reason for your answer.
15. The pictures show four ray diagrams of images formed by concave mirrors. P 3
is the pole or centre of the reflecting surface of the mirror. C is the centre of
curvature of the mirror. F is the focus of the mirror. AB is the object and A’B’
is the image of the object.