- When light strikes the boundary between two transparent media, it undergoes partial reflection and partial refraction.
- A ray passing from a rarer to a denser medium bends towards the normal, while one passing from a denser to a rarer medium bends away from the normal.
- The angles of incidence and refraction are generally unequal, causing light to bend.
- A ray incident normally (i = 0°) passes undeviated, even though its speed changes.
- Refraction occurs due to a change in the speed of light when it passes from one medium to another.
Definitions [10]
Define the principal focus of a concave mirror.
Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.
Definition: Refraction of Light
When travelling obliquely from one medium to another, the direction of propagation of light in the second medium changes. This phenomenon is known as refraction of light.
OR
Light changes its direction when going from one transparent medium to another transparent medium. This is called the refraction of light.
OR
The bending of the light ray from its path in passing from one medium to the other medium is called 'refraction' of light.
Definition: Refracted Light
Refracted light is the part of light enters into the other medium and travels in a straight path but in a direction different from its initial direction and is called the refracted light.
Definition: Refraction
The change in the direction of the path of light when it passes from one transparent medium to another transparent medium is called refraction. The refraction of light is essentially a surface phenomenon.
Definition: Lateral Displacement
The perpendicular distance XY between the path of the emergent ray BC and the direction of the incident ray OD is called the lateral displacement.
Define the term refractive index of a medium in terms of velocity of light.
It is defined as the ratio of the velocity of light in medium 1 to the velocity of light in medium 2.
Define the absolute refractive index of a medium.
The absolute refractive index is the ratio of the velocity of light in a vacuum to that of the medium.
`n = c/v`
Definition: Lateral Displacement
The perpendicular distance XY between the path of the emergent ray BC and the direction of the incident ray OD is called the lateral displacement.
Define the term refractive index of a medium in terms of velocity of light.
It is defined as the ratio of the velocity of light in medium 1 to the velocity of light in medium 2.
Define the absolute refractive index of a medium.
The absolute refractive index is the ratio of the velocity of light in a vacuum to that of the medium.
`n = c/v`
Theorems and Laws [2]
A ray of light moves from a rare medium to a dense medium as shown in the diagram below. Write down the number of the ray which represents the partially reflected ray.
Ray 2 shows partially reflected ray.
A ray of light moves from a rare medium to a dense medium as shown in the diagram below. Write down the number of the ray which represents the partially reflected ray.
Ray 2 shows partially reflected ray.
Key Points
Key Points: Refraction of Light
Key Points: Refraction of Light Through a Rectangular Glass Block
- In a rectangular glass block, the emergent ray is parallel to the incident ray, but laterally displaced.
- The angle of emergence (e) is equal to the angle of incidence (i).
- The perpendicular distance XY between the emergent ray and the incident ray's direction is called the lateral displacement.
- Lateral displacement increases with the thickness of the block, the angle of incidence, and the refractive index, and is greater for violet light than red light.
Key Points: Laws of Refraction
- The incident ray, the refracted ray, and the normal all lie in the same plane at the point of incidence.
- For a given pair of media, the ratio sin i/sin r = constant, where i is the angle of incidence and r is the angle of refraction.
Key Points: Refraction of Light Through a Rectangular Glass Block
- In a rectangular glass block, the emergent ray is parallel to the incident ray, but laterally displaced.
- The angle of emergence (e) is equal to the angle of incidence (i).
- The perpendicular distance XY between the emergent ray and the incident ray's direction is called the lateral displacement.
- Lateral displacement increases with the thickness of the block, the angle of incidence, and the refractive index, and is greater for violet light than red light.
Important Questions [23]
- What is refraction of light?
- The Phenomenon of Change in the Direction of Light When It Passes from One Transparent Medium to Another is Called ___________
- Match the Columns
- We can see the sun even when it is little below the horizon because of ______.
- Explain How the Formation of a Rainbow Occurs.
- Write a Short Note on Dispersion of Light.
- Define Refraction and State the Laws of Refraction.
- Explain How the Formation of a Rainbow Occurs.
- Why Do We Get a Spectrum of Seven Colours When White Light is Dispersed by a Prism?
- Draw the Diagram of Refraction of Light in Glass Slab
- Observe the Following Figure and Answer the Questions Given Under It: What Happens to the Ray of Light When It Passes from Air to Glass? What Happens to the Ray of Light When It Passes from Glass to Air? What Are the Rays Ab and Cd in the Figure Called?
- Choose the Correct Alternative and Rewrite the Following: a Glass Slab is Placed in the Path of Convergent Light. the Point of Convergence of Light
- Observe the figure and name the ray AB, ray CD, ray GH.
- Explain How Spectrum is Formed.
- When Rays of Light Are Incident on a Glass Slab Then the Incident Ray and Emergent Ray Are
- What is a spectrum?
- Choose the Correct Alternative and Rewrite the Following Sentence. a Ray of Light Strikes the Glass Slab at an Angle of 50°. What is the Angle of Incidence?
- Rewrite the Following Statement by Selecting the Correct Options: If a Ray of Light Strikes a Glass Slab at an Angle of 600 with the Surface of the Slab, the Angle of Incidence Must Be
- When a Ray of Light Travels from Air to Glass Slab and Strikes the Surface Of Separation at 90°, Then It
- Fill in the Blank and Rewrite the Completed Statement: Very Fine Particles Mainly Scatter ______ Light.
- Explain: ‘How is a Rainbow Formed’?
- Fill in the Blank:Very Fine Particles Mainly Scatter
- Give a scientific reason: Danger signals are red in colour.
