Reflection Of Light On Plane Surfaces ICSE Class-7th Goyal Brothers Physics Solutions Chapter-4 Unit-2

Reflection Of Light On Plane Surfaces Class-7th Goyal Brothers ICSE Physics Solutions Chapter-4(Light Energy) Unit-2(Reflection Of Light On Plane Surfaces). We Provide Step by Step Answers of Objectives, Fill in the blanks, Match the following, True/False, Incorrect and Correct, Question Type answers of Chapter-4(Light Energy) Unit-2(Reflection Of Light On Plane Surfaces). Visit official Website  CISCE  for detail information about ICSE Board Class-7.

Reflection Of Light On Plane Surfaces ICSE Class-7th Goyal Brothers Physics Solutions Chapter-4 Unit-2

Board ICSE
Class 7th
Subject Physics
Book Name Goyal Brothers
Chapter-4 Light Energy
Unit-2 Reflection Of Light On Plane Surfaces
Topic Solution of exercise questions
Session 2023-24

OBJECTIVE QUESTIONS

Reflection Of Light On Plane Surfaces ICSE Class-7th Goyal Brothers

Physics Solutions Chapter-4 Unit-2

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

List : reflected, normal, reflection, mirror, lateral inversion

1. Any smooth polished surface which can turn back the rays of light into the same optical medium is called mirror.

2. The angle which an incident ray makes with normal is called angle of incidence.

3. The phenomenon due to which a ray of light, travelling from one optical medium to another optical medium, bounces off from its surfaces with a change of angle is called reflected of light.

4. The phenomenon due to which the left side of an object, appears as the right side of image during reflection of light is called lateral inversion.

5. The incident ray, the normal and the reflection ray lie in the same plane at the point of incidence.

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

Question: 1. During reflection most of the rays are absorbed by the mirror.

Answer: During reflection most of the rays are reflected by the mirror.

Question: 2. Angle of incidence is equal to angle of reflection for looking glass only.

Answer: Angle of incidence is equal to angle of reflection for plane mirror only.

Question: 3. In case of plane mirror the size of the image is not equal to the size of the object.

Answer: In case of plane mirror the size of the image is equal to the size of the object.

Question: 4. Diffused reflection can take place from highly polished surfaces.

Answer: Regular reflection can take place from highly polished surfaces.

Question: 5. Plane mirrors always form real image.

Answer: Plane mirrors always form virtual image.

Que: C. Write ‘True’ or ‘False’ for the following statements :

Answer: 

Statements  True/False
1. A virtual image cannot be taken on a screen. T
2. Image formed in a plane mirror is real and erect. F
3. Diffused reflection takes place from rough surfaces. T
4. Plane mirrors are used as reflectors in the solar cookers. F
5. Regular reflection is less harmful to the eyes compared to the diffused reflection. F

Que: D. Tick (√) the most appropriate answer :

1. The image formed by a plane mirror is :

(a) virtual

(b) inverted

(c) diminished

(d) enlarged

Answer: option (a) virtual is correct.

2. The regular reflection takes place from the :

(a) walls

(b) still water

(c) stones

(d) trees

Answer: option (a) walls is correct.

3. The mirror which always forms a virtual, erect image of the same size as the object is :

(a) concave mirror

(b) plane mirror

(c) convex mirror

(d) none of these

Answer: option (b) plane mirror is correct.

4. The angle which the incident ray makes with the normal during reflection is called :

(a) angle of reflection

(b) angle of incidence

(c) both (a) and (b)

(d) none of these

Answer: option (b) angle of incidence is correct.

5. A perpendicular drawn on the point of incidence on the surface of a mirror is called :

(a) incident ray

(b) reflected ray

(c) normal

(d) none of these

Answer: option (c) normal is correct.

Que: E. Match the statements in Column A, with those in Column B :

Column A Column B
1. A perpendicular drawn on the mirror surface at the point of incidence. (a) Virtual image
2. A ray of light on striking a plane mirror retraces back its path. (b) Reflecting periscope
3. The kind of image formed in a plane mirror. (c) Zero degree
4. A device using two plane mirror inclined at 45° to a vertical tube. (d) Normal incidence
5. The magnitude of angle of incidence, when a ray strikes normally on a plane mirror. (e) Normal

Answer: 

Column A Column B
1. A perpendicular drawn on the mirror surface at the point of incidence. (a) Normal
2. A ray of light on striking a plane mirror retraces back its path. (b) Normal incidence
3. The kind of image formed in a plane mirror. (c) Virtual image
4. A device using two plane mirror inclined at 45° to a vertical tube. (d) Reflecting periscope
5. The magnitude of angle of incidence, when a ray strikes normally on a plane mirror. (e) Zero degree

STUDY QUESTIONS

Reflection Of Light On Plane Surfaces ICSE Class-7th Goyal Brothers

Physics Solutions Chapter-4 Unit-2

Question: 1. What do you understand by the term “reflection of light”?

Answer: When a ray of light approaches a smooth polished surface and the light ray bounces back, it is called the reflection of light. The incident light ray that land on the surface is reflected off the surface.

Question: 2. Define the following when reflection takes place from the surface of a plane mirror :

(a) incident ray

Answer: A ray of light that falls on any surface is called as an incident ray. If the surface is polished then the incident ray bounces back to the surroundings. This is called as reflected ray.

(b) reflected ray

Answer: The ray of light that is sent back after reflection by the mirror is called the reflected ray. The reflected ray always goes away from the mirror

(c) normal

Answer: When a ray of light falls normally on the surface of a plane mirror, the incident ray is reflected back along the same path. This is because the angle of incidence is zero, so the angle of reflection will also be zero.

(d) point of incidence

Answer: The point of incidence is the point at which light strikes the surface. The normal is a line that is drawn perpendicular to that point.

(e) angle of incidence

Answer: The angle of incidence is equal to the angle of reflection. The incident ray reflected ray and the normal at the point of incidence all lie in the same plane.

(f) angle of reflection

Answer: The angle between reflected ray and the normal at the point of incidence to a reflecting surface is known as angle of reflection.

Question: 3. State the laws of reflection of light.

Answer: The law of reflection states that the incident ray, the reflected ray, and the normal to the surface of the mirror all lie in the same plane. The angle of reflection is equal to the angle of incidence.

Question: 4. (a) What is regular reflection? Name two materials from which regular reflection takes place. What is the importance of regular reflection?

Answer: When a beam of parallel light rays is incident on a smooth and plane surface, the reflected rays will also be parallel. This type of reflection is called Regular Reflection. In this case, the angle of reflection of the light is equal to the angle of incidence and on the opposite side of the normal to the point of incidence. Reflection from a polished surface is called regular reflection.

Name two materials from which regular reflection takes place – a sheet of stainless steel and a thin sheet of aluminum.

The importance of regular reflection offers clear and sharp images, is essential in optical devices and signal transmission, and aids in scientific research.

(b) What is irregular reflection? Name two materials from which irregular reflection takes place. What is the importance of irregular reflection?

Answer: When a beam of parallel light rays is incident on a rough surface, the reflected rays scatter in different directions. This type of reflection is called irregular or diffuse reflection. In this case, the angle of reflection of the light is equal to the angle of incidence. Reflection from a rough surface is called diffuse reflection.

Name two materials from which irregular reflection takes place – wall, wood, a piece of wool.

The importance of irregular reflection for an object to be seen, it must reflect light irregularly.

Question: 5. State four characteristics of an image formed in a plane mirror.

Answer: Four characteristics of the images formed by plane mirrors are as follows:

  • The images are of the same size as that of the objects.
  • The images are formed behind the mirrors at the same distance from the mirrors as that of the objects.
  • The images formed are virtual and erect.
  • The images are laterally inverted.

Question: 6. Draw a neat diagram for the formation of an image in a plane mirror when a pencil is placed in front of it.

Answer:

Reflection Of Light On Plane Surfaces ICSE Class-7th Goyal Brothers Physics Solutions Chapter-4 Unit-2

Question: 7. State four uses of plane mirrors.

Answer: Four uses of plane mirrors:

  • They are used as looking glass.
  • They are used in solar cookers.
  • They are also used in constructing periscope which is used in submarines.
  • They are also used to make kaleidoscope, a toy which produces beautiful patterns.

Question: 8. (a) State primary colours and formation secondary colours by colour addition.

Answer: Primary colours:

  1. If we break the white colour we can get the seven colours. Red, Orange, Yellow, Green, Blue, Indigo, Violate.
  2. But among the seven colours their are three colours Red, Blue and green can produce white light. Those are called Primary colours.
  3. Primary colours are permanent colours which can not be obtained by mixing two or more different colours.

Secondary colour:

  1. By mixing two unlike primary colours we can get obtained the secondary colour.
  2. The colours are
  • Red + Blue = Magenta
  • Blue + Green = Cyan
  • Red + Green + Yellow

(b) Define colour subtraction. Describe appearance of colour of an object based on reflection and absorption.

Answer: The process of color subtraction is a useful means of predicting the ultimate color appearance of an object if the color of the incident light and the pigments are known. By using the complementary color scheme, the colors of light that will be absorbed by a given material can be determined.

— : end of Reflection Of Light On Plane Surfaces ICSE Class-7th Goyal Brothers Physics Solutions Chapter-4 Unit-2:–-

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