Q: State the laws of reflection. Draw a diagram to show incident and reflected rays.

First, we consider reflection, as shown in the diagram below for a light wave striking a surface. We identify the incoming ray as the incident ray and the outgoing ray as the reflected ray. Concomitantly, the angle\$\theta_i\$ that the incoming ray makes with a line (dashed in the diagram) normal to the surface is called the angle of incidence. The angle \$\theta_r\$ for the reflected ray is called the angle of reflect. The law of reflection states that the angle of incidence is equal to the angle of reflection, or, stated mathematically.And also the incident ray, the reflected ray, and the normal to the surface of the mirror all lie in the same plane.

Question 1

State the characteristics of the image formed by a plane mirror.

Accepted Answer

(i) Plane mirror forms an erect image.(ii) It forms a virtual image.(iii) Size of the image is same as that of the object.(iv) Image is formed at the same distance behind the mirror as the object stands in front of it.(v)Image formed is a laterally inverted image i.e., right hand side of the object seems to be the left hand side and vice-versa.

Question 2

Angle of incidence is equal to the angle of reflection. This is true :

Accepted Answer

By laws of reflection, angle of incidence is equal to the angle of reflection. Note that they may appear as unequal when surface is rough. However on a rough surface, due to the changes in the surface boundaries it appears unequal. At actually small surface area, angle of incidence equals the angle of reflection.

Question 3

Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.

Accepted Answer

Place a plane mirror on the table. Take a paper sheet and make a small hole in its center. Make sure that the light in the room is not bright. Hold the sheet normal to the table. Take another sheet and place it on the table in contact with the vertical mirror. Draw a normal line on the second sheet from the mirror. Now, light a torch on the mirror through the small hole such that the ray of light falls on the normal at the bottom of the mirror. When the ray from this hole is incident on the mirror, it gets reflected in a certain direction. You can easily observe the incident ray, reflected ray and the normal to the mirror at the point of incidence on the sheet placed on the table. This shows that the incident ray, the reflected ray, and the normal to the surface at the point of incidence all lie in the same plane.

Question 4

State the laws of reflection. Draw a diagram to show incident and reflected rays.

Accepted Answer

First,&#10;we consider reflection, as shown in the diagram below for a light wave striking&#10;a surface. We identify the incoming ray as the incident ray and the outgoing&#10;ray as the reflected ray. Concomitantly, the angle$\theta_i$  that&#10;the incoming ray makes with a line (dashed in the diagram) normal to the&#10;surface is called the angle of incidence. The angle $\theta_r$  for&#10;the reflected ray is called the angle of reflect.&#10;&#10; The law of reflection states that the angle of incidence is equal to the angle of reflection, or, stated mathematically.And also the incident ray, the reflected ray, and the normal to the surface of the mirror all lie in the same plane.

Question 5

Draw a ray diagram showing the formation of Image of a point object by a plane mirror.

Accepted Answer

showing the formation of image of a point object by a plane mirror.

Question 6

A light ray is incident normally on a plane mirror.(a) What is the angle of incidence?(b) What is the path of reflected ray?

Accepted Answer

Case (a):If a ray of light is incident normal to the surface of the plane mirror, then the angle of incidence is $0^0$, as the normal passes perpendicularly to the mirror.Case (b):The Second Law of Reflection states that the angle of incidence is always equal to the angle of reflection. Therefore, the angle of reflection is same as the angle of incidence, that is, $0^0$. So, the reflected ray will retrace the path of  the incident ray.

Question 7

What is reflection? Write the laws of reflection.

Accepted Answer

Reflection: The process of sending back the light rays which fall on polished surface is called reflection of light.Laws of reflection:(i) The angle of reflection is always equal to the angle of incidence.(ii) The incident rays, reflected rays and the normal, all lie in the same plane.

Question 8

A small hole P is made in a piece of cardboard. The hole is illuminated by a torch as shown in Fig. 16.3. The pencil of light coming out of the hole falls on a mirror.
At which point should the eye be placed so that the hole can be seen?

Accepted Answer

According to law of reflection we know in case of plane mirror the angle of reflection is equal to the angle of incidence. So,if we place the eye on point $A$ the hole can be seen.

Question 9

If the angle of incidence is $\displaystyle { 50 }^{ o }$, then calculate the angle between the incident ray and the reflected ray:

Accepted Answer

According to the law of reflection, the angle of incidence equals the angle of reflection.In this case, the angle of incidence is 50 degrees. So the angle of reflection will also be 50 degrees.So the angle between both the angle of incidence and angle of reflection is 50 + 50 = 100 degrees.

Question 10

The laws of reflection hold good for :

Accepted Answer

We know that from the laws of reflection, the incident ray, the reflected ray, and the normal to the reflecting surface all lie in the same plane. Also, the angle of reflection is equal to the angle of incidence.The laws of reflection hold good for all reflecting surfaces irrespective of their shapes whether plane or curved.

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Reflection of Light and Basic Terms Associated With It

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Quick Summary With Stories

Laws of Reflection

Reflection Due to Bending of Light

State the characteristics of the image formed by a plane mirror.

Angle of incidence is equal to the angle of reflection. This is true :

Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.

State the laws of reflection. Draw a diagram to show incident and reflected rays.

Draw a ray diagram showing the formation of Image of a point object by a plane mirror.

A light ray is incident normally on a plane mirror.
(a) What is the angle of incidence?
(b) What is the path of reflected ray?

What is reflection? Write the laws of reflection.

A small hole P is made in a piece of cardboard. The hole is illuminated by a torch as shown in Fig. 16.3. The pencil of light coming out of the hole falls on a mirror.
At which point should the eye be placed so that the hole can be seen?

If the angle of incidence is $50^{o}$ , then calculate the angle between the incident ray and the reflected ray:

The laws of reflection hold good for :

Revise with Concepts

Reflection of Light and Basic Terms Associated With It

Learn with Videos

Quick Summary With Stories

Laws of Reflection

Reflection Due to Bending of Light

State the characteristics of the image formed by a plane mirror.

Angle of incidence is equal to the angle of reflection. This is true :

Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.

State the laws of reflection. Draw a diagram to show incident and reflected rays.

Draw a ray diagram showing the formation of Image of a point object by a plane mirror.

A light ray is incident normally on a plane mirror.(a) What is the angle of incidence?(b) What is the path of reflected ray?

What is reflection? Write the laws of reflection.

A small hole P is made in a piece of cardboard. The hole is illuminated by a torch as shown in Fig. 16.3. The pencil of light coming out of the hole falls on a mirror. At which point should the eye be placed so that the hole can be seen?

If the angle of incidence is 50o, then calculate the angle between the incident ray and the reflected ray:

The laws of reflection hold good for :

A light ray is incident normally on a plane mirror.
(a) What is the angle of incidence?
(b) What is the path of reflected ray?

A small hole P is made in a piece of cardboard. The hole is illuminated by a torch as shown in Fig. 16.3. The pencil of light coming out of the hole falls on a mirror.
At which point should the eye be placed so that the hole can be seen?

If the angle of incidence is $50^{o}$ , then calculate the angle between the incident ray and the reflected ray: