# Rectilinear Propagation Of Light ICSE Class-6th Goyal Brothers Physics Solutions Chapter-5 Unit-2

Rectilinear Propagation Of Light ICSE Class-6th Goyal Brothers Physics Solutions Chapter-5 Unit-2 We Provide Step by Step Answers of Objective, True False, Incorrect and correct, Fill in the blanks, Match the following, Study Questions of Chapter-5, Light, Unit-2 (Rectilinear Propagation Of Light Pinhole Camera And Shadows). Visit official Website  CISCE  for detail information about ICSE Board Class-6.

## Rectilinear Propagation Of Light Pinhole Camera And Shadows ICSE Class-6th Goyal Brothers Physics Solutions Chapter-5 Unit-2

 Board ICSE Class 6th Subject Physics Book Name Goyal Brothers Chapter-5 Light Unit-2 Rectilinear Propagation Of Light, Pinhole Camera And Shadows Topic Solution of exercise questions Session 2023-24

### OBJECTIVE QUESTIONS

Rectilinear Propagation Of Light Pinhole Camera And Shadows ICSE Class-6th Goyal Brothers Physics Solutions Chapter-5 Unit-2

#### Que: A. Fill in the blank spaces by choosing the correct words from the list given below:

List : high, solar, shadow, straight lines, inverted

1. The pinhole camera is based on the principle that light travels in …straight lines….

2. For the formation of a …shadow… there must be an opaque body to obstruct the path of light.

3. The image formed in a pinhole camera is a always …inverted….

4. An Aeroplan flying …high… in the sky does not cast its shadow.

5. During a …solar… eclipse the shadow of the moon falls on the day side of earth.

#### Que: B. Statements given below are incorrect. Write the correct statements.

##### Question: 1. An opaque body as a screen is not necessary in the formation of a shadow.

Answer: An opaque body as a screen is necessary in the formation of a shadow.

##### Question: 2. The image formed by a pinhole camera is always virtual and erect.

Answer: The image formed by a pinhole camera is always real and inverted.

##### Question: 3. Solar eclipse takes place more frequently than the lunar eclipse.

Answer: Solar eclipse takes place less frequently than the lunar eclipse.

##### Question: 4. The size of umbra increases as the opaque body is moved away from the screen.

Answer: The size of umbra decrease as the opaque body is moved away from the screen.

##### Question: 5. Solar eclipse lasts longer than the lunar eclipse.

Answer: Solar eclipse lasts lesser than the lunar eclipse.

#### Que: C. State whether the following statements are true or false :

 Statements True/False 1. Rays of light bend on entering a pinhole camera. F 2. Lunar eclipse is caused on a new moon day. F 3. Birds flying high in the sky do not cast their shadows. F 4. Fluorescent tube lights are called shadow-less lights. T 5. A solar eclipse lasts for very small time as compared to a lunar eclipse. T

#### Column B

1. A dark patch formed behind an opaque body, when it is placed in the path of light. (a) Umbra
2. A kind of shadow where no ray of light enters. (b) Penumbra
4. Characteristics of image formed by a pinhole camera. (d) Lunar eclipse
5. A region of total darkness formed on the moon on full moon night. (e) Real and inverted

#### Column B

1. A dark patch formed behind an opaque body, when it is placed in the path of light. (a) Shadow
2. A kind of shadow where no ray of light enters. (b) Umbra
3. A kind of shadow partially illuminated by light. (c) Penumbra
4. Characteristics of image formed by a pinhole camera. (d) Real and inverted
5. A region of total darkness formed on the moon on full moon night. (e) Lunar eclipse

### STUDY QUESTIONS

Rectilinear Propagation Of Light Pinhole Camera And Shadows ICSE Class-6th Goyal Brothers Physics Solutions Chapter-5 Uni-2

#### 1. Briefly describe an experiment to prove that light travels in straight lines.

Answer: Take three cardboard pieces of similar dimension and make a hole in the center of each. Align these three cardboard parallel to each other in such a way that all the holes are exactly along the same line. Now, take a lit candle, align it at one end and view the candle from the other end.

You will only be able to see the candle if the holes in the cardboard are all in a straight line. Even if one cardboard is moved to the left or right, your view of the candle will be blocked. This shows that light travels in a straight line.

#### 2. (a) What is the principle of a pinhole camera?

Answer: Pinhole cameras rely on light traveling in straight lines – a principle called the rectilinear light theory. That makes the camera’s picture appear upside-down. And from the description above we can infer that the pinhole camera works on the theory of rectilinear light propagation. So this is the required answer.

#### (b) Briefly describe the construction and working of a pinhole camera. Draw a diagram in support of your answer.

Answer: A pinhole camera is a light-proof box with a tiny hole in one side that doesn’t have a lens but does have a small aperture. The camera obscura effect occurs when light from an item travels through the aperture and projects an inverted picture on the opposite side of the box.

#### 3. (a) State three characteristics of an image formed by a pinhole camera.

Answer: Three characteristics of an image formed by a pinhole camera:

• A real image is obtained as the image is obtained on the screen.
• The size of the image obtained is comparatively smaller than the actual object.
• The image is inverted on the x-axis as well as on the y-axis.

#### (b) How is the image formed in a pinhole camera affected when (i) the distance of screen from the pinhole increases, (ii) the distance of the object from the pinhole increases ?

Answer: If the distance between the pinhole and screen is increased, the image size will increase and the image however will get less bright since the light spreads over a large area.

#### 4. (a) What is a shadow? State three conditions for the formation of shadow.

Answer: A shadow is a dark area where light from a light source is blocked by an opaque object. The things necessary for the formation of a shadow are:

• A source of light
• An opaque object whose shadow has to be formed
• A screen on which shadow is to be formed

#### (b) Define the terms : (i) Umbra, (ii) Penumbra.

Answer: (i) Umbra region is that region from which all direct sunlight is excluded during solar eclipse. (ii) Penumbra region is that region of diffused sunlight during the solar eclipse.

#### 5. By drawing a neat diagram show the formation of shadow, when the extended source of light is smaller than the opaque body. How are the umbra and penumbra shadows affected when the screen is moved away from the opaque body?

Answer: The inner patch is completely dark as it does not get any light. This region is called umbra. The outer patch is not completely dark as it receives some light. This lighter patch of shadow is called penumbra.

If the screen is moved away from the object and from the light source , the size of the umbra becomes smaller and smaller. Beyond a point, the umbra completely vanishes. Both umbra and penumbra are formed. However, size of the umbra is smaller than the penumbra.

#### 6. By drawing a neat diagram show the formation of shadow, when the extended source of light is bigger then the opaque body. How are the umbra and penumbra affected when the screen is moved away from the opaque body?

Answer: When the extended source of light is bigger than the opaque body the penumbra region is bigger than the size of umbra region. A penumbra is that region around the umbra where the shadow is only partial, or imperfect. If the screen is moved away from the object, the umbra vanishes and only the penumbra remains.

#### 7. By drawing a diagram explain, why the birds flying high in the sky do not cast their shadows.

Answer: The birds flying in the sky do not cast their shadow on the earth because the umbra is absent and the penumbra is too large and too faint that it is not visible as the distance of earth is very large from the bird.

#### 8. Why are fluorescent tube lights called shadowless lights?

Answer: Fluorescent tube light is considered shadowless light Because, in most cases, umbra finishes in the air and penumbra is so light that is hardly visible.

#### 9. (a) What is a solar eclipse? Support your answer by a neat diagram.

Answer: A solar eclipse occurs when the moon passes between the earth and the sun, thereby obscuring Earth’s view of the Sun, totally or partially. Such an alignment coincides with a new moon indicating the Moon is closest to the plane of the earth’s orbit In a total eclipse. The disk of the Sun is fully obscured by the Moon. In partial and annular eclipse only part of the Sun is obscured.

#### (b) Why does a solar eclipse last for a very small time?

Answer: A total solar eclipse only lasts for a few minutes. This is because the Moon’s shadow moves at 1,700 kilometers per hour! A total solar eclipse occurs on Earth roughly every 18 months. But the Moon’s shadow only covers a part of the Earth’s surface.

#### (c) Why is a total solar eclipse not very frequent?

Answer: If the Earth and moon orbited on the same plane around the sun, we’d have a total solar eclipse – and a total lunar eclipse – every month. But we don’t, because the moon’s orbit is inclined to Earth’s orbit by about 5 degrees.

#### 10. (a) What is a lunar eclipse? Support your answer by a neat diagram.

Answer: A lunar eclipse occurs when the Sun, Earth, and Moon align so that the Moon passes into Earth’s shadow. In a total lunar eclipse, the entire Moon falls within the darkest part of Earth’s shadow, called the umbra.

#### (b) Why dose a lunar eclipse last longer than a solar eclipse?

Answer: The lunar eclipse duration is much more than the solar eclipse. It happens due to the reason that the earth’s diameter is greater than the moon. Hence, the shape of the earth’s shadow totally engulfs the moon for a longer period of time.

#### (c) Why is a lunar eclipse more frequent compared to a solar eclipse?

Answer: Lunar eclipses are more frequently visible because during a lunar eclipse, Earth casts a much bigger shadow on the Moon than the Moon casts during a solar eclipse on Earth. The reason solar eclipses are so rare is that the umbra of the Moon rarely hits the surface of the Earth.

#### 11. Why should a solar eclipse not be seen with naked eyes? How is a solar eclipse seen? Explain.

Answer: Solar eclipse should never be viewed directly. This is because during a solar eclipse, the Earth receives a lot of UV radiations. These radiations can burn the retina of the eye and hence one can lose the eyesight permanently.

— : End Rectilinear Propagation Of Light Pinhole Camera And Shadows ICSE Class-6th Goyal Brothers Physics Solutions Chapter-5 Unit-2 :–-