Telangana SCERT Class 8 Physical Science Chapter 6 Reflection of Light by Plane Surfaces Solution

Telangana SCERT Class 8 Physical Science Chapter 6 Solution – Reflection of Light by Plane Surfaces. Here in this post we provides Class 8 Physical Science Reflection of Light by Plane Surfaces Telangana State Board Solution.  Telangana State Board English Class VIII Medium Students can download this Solution to Solve out Improve Your Learning Questions and Answers.

Telangana State Board Class 8 Physical Science Chapter 6 Reflection of Light by Plane Surfaces Solution:

(1) If a ray incidents normally on a plane mirror, what will be the angle of reflection?

Ans: – When the light ray is incident normally on plane mirror, then by using lows of reflection ang;e of incidence is equal to angle of reflection.

Angle of incidence = Angle of reflection means if the angle of incidence is ‘O’ degree, then angle of reflection is also ‘O’ degree.

(2) Explain the laws of reflection?

Ans: – Laws of reflection –

(i) The angle of incidence is equal to the angle of reflection.

(ii) The incident ray, the reflected ray and the normal all lie in the same plane.

(3) Explain the process of formation of an image with a pinhole camera? Draw a ray diagram to show this.

Ans: – a pinhole camera is a simple camera with a tiny hole mean pinhole.

The light from candle travels points in all directions fr0m each point of the flam of candle.

But through the cameras pinhole only the light comes in some particular direction can enter.

Light which comes from the point at the top of the phone goes straight to the bottom of the screen and the light which comes from the point at the bottom of the plane goes straight towards the top of the screen.

(4) Why does the image plane mirror suffer lateral inversion?

Ans: – The reason is that the light rays which come from the object get reflected from the plane mirror and reach to our eyes. Our brain feels that the ray (reflected ray) is coming from the inside of the mirror. That is why the right of object looks like left in the image. So the image in plane mirror suffers lateral inversion.

(5) Draw a ray diagram to understand the formation of image for a pointed object by a plane mirror? Explain it.

Ans: –

Explain: – In this figure, O is a point object. Some rays from O reach the mirror and get reflected. When we look into the mirror, the reflected rays seem to be coming from the point I. So point I is the image of point object O.

Observance the distances of object. O and image I from the surface of the mirror and try to compare these distances and you find that these distances are equal.

(II) Application of concepts

(1) In the adjacent figure, AO and OB are incident and reflected rays respectively. AOB = 90o. Find the values of angle of incidence and angle of reflection?

Ans: –

I assume point C at normal.

As we know Angle of incidence = Angle of reflection

So,

∠AOC + ∠BOC = 90o

AS ∠AOC = ∠BOC

∠AOC + ∠AOC = 90o

2∠AOC = 90o

∴ ∠AOC = 90o /2

∠AOC = 45o

That means ∠BOC = 45o

So, the angle of reflection and incidence will be 45o

(2) Bharath stands in fornt of a plane mirror at a distance of 5m. from the mirror and observes his image in the mirror. If he moves 2m. towards the plane mirror, then what will be the distance between Bharath and his image?

Ans: – The distance between bharat and his image will be 6 meters.

5 – 2 = 3

Because the distance between mirror and Bharat is reduced to 3 m.

So same in his image

3 + 3 = 6 meters.

As we know the distance between the object and the plane mirror is equal to the distance between the image and the plane mirror.

(3) Explain diagrammatically the image of letter ‘B’ in a plane mirror.

Ans: – The image of the letter B in the mirror will looks like this –

(4) Why can’t we see our image in a white sheet of paper though it reflects light?

Ans: – Actually the white sheet of papers is not flat, not smooth. There are tiny rough spots that we cannot feel. That means it do not have the reflecting quality, so it does not reflect light. But if it reflects then it reflects multiple reflection, then scatters the reflecting rays of the image and then we lost the image.

(5) Discuss the merits and demerits of using mirrors in building elevation?

Ans: – The merits of using mirrors in building elevation –

(i) The mirrors make the building attractive.

(ii) We can have good and correct view of the interior and exterior design

The demerits are

*Light of reflection can take place on this mirror.

*Some mirrors that are used in buildings can easily broke down, so when it brokes then buildings loses its attraction.

(III) Higher Order Thinking Questions.

(1) Observe the adjacent figure. AB and BC are two plane mirrors arranged at 120o. A ray incidents at and angle 55o on AB. Find the value of ‘x’?

Ans: –

As we know that Angle of incidents = Angle of reflection

55o + z = 90o

Z = 90o – 55o

= 35o

Z + y + 120o = 180o

Y = 180o – 120o – z

= (180o – 120o) – 35o

= 60o – 35o

= 25o

x + y = 90o

x = 90o – 25o = 65o

(2) Niharika holds a clock in her hand, which shows the time 3’O clock. If she observes the clock in aplane mirror, what will be the time that the clock shows in the plane mirror?

Ans: – She will observe that the clock in the mirror reflection is showing the time of 9 o’clock

This happens due to the vertical flipping.

(4) Two divergent rays originationg from the same point have and angle of 10o between them. If they strike a plane mirror with same incident angle, what will be the angle of reflection?

Ans: – If they strike a plane mirror with same incident angle 5o will be the angle of reflection.

(5) The size of the image in the mirror seem to bedecreased when you move the object towards your eye from the mirror. Draw the diagram showing angles depicting the situation.

Ans: –

Multiple choice questions

(1) Angle of incidence = Angle of reflection. This rule is explained by __________ principle.

Ans: – (D) Pascal

(2) Which of the following letters doesn’t suffer lateral inversion

Ans: – (B) O

(3)  A ray of light incidents on a plane mirror at an angle of 90o to its surface. What will be the angle of reflection

Ans: – (B) 90o

(4) If we move an object away from the plane mirror the size of images seems to be

Ans: – (C) of the same size

(5) Which of the following is incorrect with respect to the image in a plane mirror

Ans: – (D) Image is real

Updated: September 3, 2020 — 2:37 pm

4 Comments

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  1. It was very easy to complete my Fair Notes. Thank You for posting these answers in web. Can you post all other subjects ???? Please post 8,9 and 10 classes notes. Please I’m begging you a lot. Anyways Thank You for posting these answers……

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  3. Yes it is easy to learn and write

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