1. Observe the picture given in fig 11.1 carefully.
When lit as depicted, the torch produces a patch of light at B. To obtain this patch of light, which of the following is maintained at location A?
(b) a sheet of glass
(c) One that reflects
(d) a piece of white paper, fix:
1. Observe the picture given in fig 11.1 carefully.
When lit as depicted, the torch produces a patch of light at B. To obtain this patch of light, which of the following is maintained at location A?
(b) a sheet of glass
(c) One that reflects
(d) a piece of white paper, fix:
Explanation:
Mirror (c)
A patch of light can only be reflected and redirected by a mirror.
2. A student uses a pinhole camera to capture images of the tree shown in the picture. Which of the illustrations in figures
(a) through (d) appropriately reflects the picture she saw?
2. A student uses a pinhole camera to capture images of the tree shown in the picture. Which of the illustrations in figures
(a) through (d) appropriately reflects the picture she saw?
Explanation:
(b): The visual that the student saw is accurately depicted in Option.
She will look at the tree's lateral inverted upside-down representation.
3. As seen in fig. 11.4, four students, A, B, C, and D, peered through pipes of various shapes to see a candle flame.
Who will be able to clearly observe the candle's flame?
(a) A
(b) B
(c) C
(d) D
3. As seen in fig. 11.4, four students, A, B, C, and D, peered through pipes of various shapes to see a candle flame.
Who will be able to clearly observe the candle's flame?
(a) A
(b) B
(c) C
(d) D
Explanation:
(d) In a straight path, light moves.
4. Which of the following statements about shadow observation is/are true?
(A) the sun
(B) a screen
(C) a light source
(D) an opaque item
4. Which of the following statements about shadow observation is/are true?
(A) the sun
(B) a screen
(C) a light source
(D) an opaque item
Explanation:
(a) the Sun
Sunlight is not always required to see a shadow.
A source of light is the sun. Any other source of light, such as a torch, can take its place.
5. Paheli noticed a tree's shadow at 8:00, 12:00, and 3:00 in the afternoon. Which of the following statements best describes how she observed the shadow's size and shape?
(A) The tree's shadow changes in size while maintaining its shape.
(b) The shape of the tree's shadow doesn't alter, only its size.
(c) The tree's shadow changes in both size and shape.
(d) The shadow remains the same size and shape.
5. Paheli noticed a tree's shadow at 8:00, 12:00, and 3:00 in the afternoon. Which of the following statements best describes how she observed the shadow's size and shape?
(A) The tree's shadow changes in size while maintaining its shape.
(b) The shape of the tree's shadow doesn't alter, only its size.
(c) The tree's shadow changes in both size and shape.
(d) The shadow remains the same size and shape.
Explanation:
(c): The tree's shadow changes in both size and shape.
Since the Sun is the source of light, it moves in different places at different times. As a result, the tree's shadow changes in size and shape.
6. Which of the subsequent cannot ever produce a circular shadow?
(b) a ball
(b) flat disc
(c) shoe box
(d) a cone of ice cream
6. Which of the subsequent cannot ever produce a circular shadow?
(b) a ball
(b) flat disc
(c) shoe box
(d) a cone of ice cream
Explanation:
(c) A box of shoes
The shape of a shoebox is either square or rectangular.
7. Sitting across from each other at a table, two students peered down at its top. They became aware of being able to view both their own and one another's images. The table top will probably be built of one of the following materials:
(a) unpolished wood
(b) red stone
(c) glass sheet
(d) wood top covered in fabric
7. Sitting across from each other at a table, two students peered down at its top. They became aware of being able to view both their own and one another's images. The table top will probably be built of one of the following materials:
(a) unpolished wood
(b) red stone
(c) glass sheet
(d) wood top covered in fabric
Explanation:
(c): Sheet of glass
To effectively reflect light and create their images, only the glass sheet is capable of doing so.
(d) A cloth-covered wood top.
8. As seen in fig. 11.5, you have three opaque strips with teeny, tiny holes of various shapes. Will the image created by these holes be the same as the sun's image on a wall, or will it be different?
8. As seen in fig. 11.5, you have three opaque strips with teeny, tiny holes of various shapes. Will the image created by these holes be the same as the sun's image on a wall, or will it be different?
Explanation:
The three things together create the same imagery. These opaque strips will function as pinholes, creating an image of the sun on the wall.
9. Examine the image in fig. 11. 6. The patch of light is still visible on the screen despite a sheet of material being positioned at location "P." What kind of material is this sheet made of?
9. Examine the image in fig. 11. 6. The patch of light is still visible on the screen despite a sheet of material being positioned at location "P." What kind of material is this sheet made of?
Explanation:
Only transparent materials allow light to travel through them, hence sheet P must be made of a transparent material to do so.
10. The three lamps A, B, and C, which are depicted in fig. 11.7, are turned on one by one. Whichever torch's light does not cast a shadow of the ball on the screen.
10. The three lamps A, B, and C, which are depicted in fig. 11.7, are turned on one by one. Whichever torch's light does not cast a shadow of the ball on the screen.
Explanation:
Light, as we all know, moves in a straight line. The shadow of the ball on the screen won't be created by the light from torch C. It is impossible for light to travel through the screen since torch C is positioned parallel to it.
11. Look at the given figure.
Will the shadows cast on the screens in A and B differ in any way?
Will the shadows cast on the screens in A and B differ in any way?
Explanation:
No, the shadows cast on screens A and B will be identical.
12. Rephrase the ensuing statements.
(i) The colour of an object affects the colour of the shadow it casts.
(ii) Light can partially flow through transparent objects.
12. Rephrase the ensuing statements.
(i) The colour of an object affects the colour of the shadow it casts.
(ii) Light can partially flow through transparent objects.
Explanation:
(i) As the shadow is typically dark in colour, the colour of the object does not depend on the colour of the shadow.
(ii) Most of the light can travel through transparent objects. Light can partially flow through translucent objects.
13. Imagine a scenario in which we can see many shadows of the same item at once.
13. Imagine a scenario in which we can see many shadows of the same item at once.
Explanation:
(i) If an item receives light from multiple sources, we can obtain more than one shadow of it at once.
(ii) A cricket stadium, for instance, allows us to see many shadows of players due to the various angles from which the light hits them.
14. Does a bird or an aeroplane casting its shadow on the ground on a sunny day? What conditions allow us to perceive their shadow on the ground?
14. Does a bird or an aeroplane casting its shadow on the ground on a sunny day? What conditions allow us to perceive their shadow on the ground?
Explanation:
No, even on a sunny day, a bird or an aeroplane flying high in the sky cannot cast its shadow on the ground since they are at a higher altitude than the item can get its shadow.
If they are flying very close to the ground, we can only see their shadow on the surface.
15. A transparent glass sheet is provided to you. Make it transparent in any two ways without breaking it, please.
15. A transparent glass sheet is provided to you. Make it transparent in any two ways without breaking it, please.
Explanation:
Without breaking it, a clear glass sheet can be transformed into a translucent glass sheet by:
(i) Coating it with grease, butter, oil, or butter paper.
(ii) Sandpaper or any other abrasive material being used to rub the glass' surface.
16. As shown in fig. 11.9, a torch is put sequentially at places A and B.
Figure 11.10 depicts the shape of the shadow obtained in two positions.
Match the torch's position with the ball's shadow's shape.
16. As shown in fig. 11.9, a torch is put sequentially at places A and B.
Figure 11.10 depicts the shape of the shadow obtained in two positions.
Match the torch's position with the ball's shadow's shape.
Explanation:
A → a;
The shadow "a" will be formed by Position A.
B → b
The shadow "b" will be formed by position B.
We can see how the shadow's shape varies as the torch's position does.
17. To obtain red light, a pupil covered a torch with a red cellophane sheet. She captures the shadow of an opaque item with the red light. Her actions are repeated using both green and blue light. Will the shadow be impacted by the colour of the light? Explain.
17. To obtain red light, a pupil covered a torch with a red cellophane sheet. She captures the shadow of an opaque item with the red light. Her actions are repeated using both green and blue light. Will the shadow be impacted by the colour of the light? Explain.
Explanation:
No, the colour of the light won't change the shadow because a shadow is typically a dark or black patch that forms when something blocks the path of the light and no light gets to that area.
18. Is the atmosphere surrounding us always clear? Discuss.
18. Is the atmosphere surrounding us always clear? Discuss.
Explanation:
Absolutely, because of the transparency of the air around us, objects are visible to our eyes. When the air is filled with smoke, clouds, etc., it loses its transparency and becomes difficult to see.
19. Three identical towels in the colours red, blue, and green are drying in the sun on a clothesline. What shade would these towels' shadows be?
19. Three identical towels in the colours red, blue, and green are drying in the sun on a clothesline. What shade would these towels' shadows be?
Explanation:
Typically, a shadow is dark or black in colour. As a result, all three towels' shadows will have the same colour because no light will shine through them.
20. A student examines the image of two of his pals wearing red and yellow shirts, respectively, while they stand in the sunlight using a pinhole camera. What shades of shirts will there be in the picture?
20. A student examines the image of two of his pals wearing red and yellow shirts, respectively, while they stand in the sunlight using a pinhole camera. What shades of shirts will there be in the picture?
Explanation:
A pinhole camera does not alter the image's colour. The shirts' actual colours will not change from those in the illustration. But, when using a pinhole camera, the person's image will be inverted.
21. In fig. 11.11, a thick coloured paper blossom has been adhered to the clear glass sheet. What colour and shape will the shadows appear to be on the screen?
21. In fig. 11.11, a thick coloured paper blossom has been adhered to the clear glass sheet. What colour and shape will the shadows appear to be on the screen?
Explanation:
The shadow that is created will have the shape of a flower with its stalk and be black in colour.
22. There is a football game being played at night under floodlights in a stadium. When a football is kept on the ground, its shadow may be seen, but when it is kicked far into the air, it is invisible. Explain.
22. There is a football game being played at night under floodlights in a stadium. When a football is kept on the ground, its shadow may be seen, but when it is kicked far into the air, it is invisible. Explain.
Explanation:
Because the ground serves as a screen for it, we can see the shadow of the football that is laying on the ground. The shadow of the football, however, cannot be seen when it is in the air since it disappears with height and will be far from the ground when the football is kicked far into the air.
23. A student had a functioning flashlight, ball, and screen. By arranging them in various configurations, he attempted to create a shadow of the ball on the screen. Sometimes it wasn't possible to get a shadow. Explain.
23. A student had a functioning flashlight, ball, and screen. By arranging them in various configurations, he attempted to create a shadow of the ball on the screen. Sometimes it wasn't possible to get a shadow. Explain.
Explanation:
Some of the barriers to obtaining shadow include
(i) The ball is far from the screen.
(ii) On the ball, the torch's light beam is descending perpendicular to the screen.
(iii) The torch is kept away from the ball in item.
24. In the configuration indicated in fig. 11.12, a sheet of plywood, a piece of muslin cloth, and a piece of transparent glass were sequentially inserted at A. Will the shadow appear in every situation? If so, how will each case's shadow on the screen differ from the others? Explicitly justify your response.
24. In the configuration indicated in fig. 11.12, a sheet of plywood, a piece of muslin cloth, and a piece of transparent glass were sequentially inserted at A. Will the shadow appear in every situation? If so, how will each case's shadow on the screen differ from the others? Explicitly justify your response.
Explanation:
In none of the scenarios will a shadow develop. Only the plywood sheet and the muslin fabric will make a shadow on the screen.
(i) Because the muslin material allows some light to flow through it, the shadow it casts will be lighter.
(ii) The plywood sheet will cast a dark shadow because it totally blocks the light's passage.
(iii) Most of the light will be able to travel through the transparent glass. Hence, no shadow will appear on the screen.
