What is the branch of physics that deals with the wave theory of light?
Wave Optics
Who proposed the wave theory of light and in what year?
Christian Huygen in 1679
How can a wave be described?
As a disturbance that travels through a medium from one location to another
What is the important characteristic of a wave?
There is no net movement of particles, but energy can be transferred
What is a wavefront?

A surface where all particles are equidistant from the source and vibrating in the same phase
How is a ray of light related to a wavefront?
A ray of light is always perpendicular to the wavefront
What is the phase difference between any two points on the same wavefront?
The phase difference is zero
What are the properties of a wavefront?

The particles on the wavefront have equal distance from the source and the same phase of vibration
What type of wavefront is generated by a point source of light?
Spherical wavefront
What is a converging spherical wavefront?
It is obtained from light rays coming out of a convex lens
What is a diverging spherical wavefront?
It is obtained from light coming out of a concave lens
What type of wavefront is generated by a linear source of light?
Cylindrical wavefront
What type of wavefront is produced when the source of light is at a large distance?
Plane wavefront
What does Huygen’s Principle allow us to do?
It allows us to locate a new wavefront if the position of the earlier wavefront is known
How do you construct a new position of a wavefront using Huygen’s Principle?
By drawing spheres of radii ct from points on the same wavefront and drawing an envelope of these spheres
What is the formula for the refractive index (μ) of a medium?

μ = c/v
What happens to the frequency of light when it travels from one medium to another?
The frequency remains constant
How do wavelength and speed of light change with the change in medium?
They are inversely proportional to the refractive index of the medium
What is the significance of Huygen’s Principle?
It explains the propagation of wavefront in the medium and determines the position of wavefront after any instant of time
How does Huygen’s Principle apply to the laws of reflection?

It shows that the angle of incidence equals the angle of reflection
What is the law of reflection?
The angle of incidence is equal to the angle of reflection
What is the relationship between the angles of incidence and reflection in Huygen’s Principle?
They are equal
How does Huygen’s Principle apply to the laws of refraction?
It helps to determine the angles of incidence and refraction at the boundary of two media
What are wavelets in the context of Huygen’s Principle?
Wavelets are disturbances coming out of secondary sources, not directly from the primary source
How do secondary wavelets travel in relation to the primary wavefront?
They travel in all directions with the speed of the primary wavefront
What is the relationship between wavelength and frequency in wave optics?
Wavelength and frequency are related by the equation v = λf
What does the RHS rule state in the context of triangle congruence?
If the hypotenuse and one side of a right-angled triangle are equal to the hypotenuse and corresponding side of another right-angled triangle, then the triangles are congruent
How does the congruence of triangles relate to the law of reflection?
It shows that the angles of incidence and reflection are equal due to the congruence of the triangles formed
What is the condition for two triangles to be congruent?
If two angles are equal, then two triangles are congruent.
What does the law of reflection state?
The angle of incidence is equal to the angle of reflection.
What are the symbols used to represent the incident rays and refracted rays in the study of refraction?
I1 and I2 represent the incident rays, while R1 and R2 represent the refracted rays.
What does Huygen’s Principle relate to in the context of refraction?
It describes how wavefronts propagate through different media.
What is the refractive index of a medium represented by?

μ (mu)
What is the relationship between the angle of incidence and the angle of refraction in terms of the refractive index?
The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant, known as the refractive index.
How can Snell's law be expressed in terms of the velocities of light in two different media?
The ratio of the velocities of light in two media is equal to the ratio of their refractive indices.
What does the principle of superposition of light waves state?
It states that the resultant displacement of overlapping light waves is the vector sum of their individual displacements.
What is interference of light waves defined as?
It is the phenomenon of redistribution of light intensity due to the superposition of two or more light waves.
What is necessary for interference to be observed?
The two light sources must be coherent.
What is constructive interference?

It occurs when the crest of one wave overlaps with the crest of another wave, resulting in increased light intensity.
What is destructive interference?

It occurs when the crest of one wave overlaps with the trough of another wave, resulting in decreased light intensity.