In this article, we will provide you with solutions to the NCERT questions of Light, Shadows and Reflections. This chapter in Class 7 Curiosity covers important topics such as luminous and non-luminous objects, shadows, transparent and opaque objects, pinhole camera, mirrors, and reflection of light. These solutions are written in very simple and easy language so that students can understand the chapter quickly and prepare well for exams and homework.
Light, Shadows and Reflections NCERT Solutions
Q1. Which of the following are luminous objects?
Mars, Moon, Pole Star, Sun, Venus, Mirror
Answer:
Sun and Pole Star are luminous objects because they give their own light.
Q2. Match the items in Column A with those in Column B.
Answer:
- Pinhole camera – Forms an inverted image
- Opaque object – Blocks light completely
- Transparent object – Light passes almost completely through it
- Shadow – The dark region formed behind the object
Q3. Sahil, Rekha, Patrick, and Qasima are trying to observe the candle flame through the pipe as shown in Fig. 11.16. Who can see the flame?
Answer:
Qasima can see the flame because light travels in a straight line.
Q4. Look at the images shown in Fig. 11.17 and select the correct image showing the shadow formation of the boy.
Answer:
Image (c) is correct.
Q5. The shadow of a ball is formed on a wall by placing the ball in front of a fixed torch as shown in Fig. 11.18. In scenario (i) the ball is close to the torch, while in scenario (ii) the ball is closer to the wall. Choose the most accurate representation of the shadows formed in both scenarios from the options provided (a and b).
Answer:
- In scenario (i), shadow (b) is correct because the shadow becomes larger when the ball is near the torch.
- In scenario (ii), shadow (a) is correct because the shadow becomes smaller when the ball is near the wall.
Q6. Based on Fig.11.18, match the position of the torch in Column A with the characteristics of the ball’s shadow in Column B.
Answer:
- If the torch is close to the ball – The shadow would be larger
- If the torch is far away – The shadow would be smaller
- If the ball is removed from the set-up – A bright spot would appear on the screen
- If two torches are present in the set-up on the left side of the ball – Two shadows would appear on the screen
Q7. Suppose you view the tree shown in Fig. 11.19 through a pinhole camera. Sketch the outline of the image of the tree formed in the pinhole camera.
Answer:
The image formed in the pinhole camera will be upside down.
Q8. Write your name on a piece of paper and put it in front of a plane mirror such that the paper is parallel to the mirror. Sketch the image. What difference do you notice? Explain the reason for the difference.
Answer:
The image in the mirror appears reversed from left to right. This happens because a plane mirror forms a laterally inverted image.
Q9. Measure the length of your shadow at 9 AM, 12 PM, and 4 PM with the help of your friend. Write down your observations:
(i) At which of the given times is your shadow the shortest?
(ii) Why do you think this happens?
Answer:
(i) The shadow is shortest at 12 PM.
(ii) At 12 PM, the Sun is almost overhead, so the shadow becomes small.
Q10. On the basis of following statements, choose the correct option.
Statement A: Image formed by a plane mirror is laterally inverted.
Statement B: Images of alphabets T and O appear identical to themselves in a plane mirror.
(i) Both statements are true
(ii) Both statements are false
(iii) Statement A is true, but statement B is false
(iv) Statement A is false, but statement B is true
Answer:
(i) Both statements are true.
Q11. Suppose you are given a tube of the shape shown in the Fig. 11.20 and two plane mirrors smaller than the diameter of the tube. Can this tube be used to make a periscope? If yes, mark where you would fix the plane mirrors.
Answer:
Yes, the tube can be used to make a periscope. The two plane mirrors should be fixed at both bent ends of the tube at an angle.
Q12. We do not see the shadow on the ground of a bird flying high in the sky. However, the shadow is seen on the ground when the bird swoops near the ground. Think and explain why this is so.
Answer:
When the bird is very high, its shadow becomes very faint and spread out, so we cannot see it clearly. When the bird comes near the ground, the shadow becomes dark and clear. Because light spreads out over a large area when the bird is very high in the sky. So, the shadow becomes very light and blurry, and our eyes cannot see it clearly. When the bird comes closer to the ground, the shadow forms in a smaller area. So, it becomes darker and sharper, and we can see it easily.