<–2/”>a >Ray Optics
The wave model of Light has one serious drawback, though: Unlike other wave phenomena such as Sound, or surface waves, it wasn‟t clear what the medium was that supported light waves. Giving it a name – the “luminiferous aether” – didn‟t help. James Clerk Maxwell‟s (1831 – 1879) theory of electromagnetism, however, showed that light was a wave in combined electric and magnetic fields, which, being force fields, didn‟t need a material medium.
Light waves are Electromagnetic Waves, whose nature is transverse. The speed of light in vacuum is 3 x 10 m/s but it is different in different media.
The speed and wavelength of light change when it travels from one medium to another but its frequency remains unchanged.
Light is electromagnetic radiation that has properties of waves. The electromagnetic spectrum can be divided into several bands based on the wavelength. As we have discussed before, visible light represents a narrow group of wavelengths between about 380 nm and 730 nm.
Our eyes interpret these wavelengths as different colors. If only a single wavelength or limited range of wavelengths are present and enter our eyes, they are interpreted as a certain color. If a single wavelength is present we say that we have monochromatic light. If all wavelengths of visible light are present, our eyes interpret this as white light. If no wavelengths in the visible range are present, we interpret this as dark.
We have further sub-divided the topic into following Topics:-
Reflection and Refraction
Specular and diffuse reflection
Refraction and Snell’s law
Snell’s law
Dispersion
Mirrors
Virtual image
Parabolic mirrors and real images
Lenses
Convex lenses
Concave lenses
Object image Height and Distance relationship
Thin lens equation
Multiple lens systems
Diopters, Aberration, and the Human Eye,
Ray optics is the study of light as a collection of rays. It is a simplified model of light that is useful for understanding many optical phenomena. In ray optics, light is assumed to travel in straight lines, and the laws of reflection and refraction are used to predict the behavior of light rays.
Reflection is the bouncing of light off a surface. The angle of incidence, which is the angle between the incoming light ray and the normal (an imaginary line perpendicular to the surface), is equal to the angle of reflection, which is the angle between the outgoing light ray and the normal.
Refraction is the bending of light as it passes from one medium to another. The amount of refraction depends on the refractive indices of the two media. The refractive index is a measure of how much light bends when it passes from one medium to another. The refractive index of air is 1.0003, while the refractive index of water is 1.33. This means that light bends more when it passes from air to water than it does when it passes from air to vacuum.
Diffraction is the bending of light as it passes around an obstacle or through a narrow opening. Diffraction is caused by the wave nature of light. When light waves pass through a narrow opening, they interfere with each other, causing the light to spread out.
Interference is the interaction of two or more waves. When two waves of the same wavelength meet, they can either add together or cancel each other out, depending on the phase difference between them. Phase difference is the difference in the positions of two waves at a given time. If the waves are in phase, they add together to create a wave with a larger amplitude. If the waves are out of phase, they cancel each other out to create a wave with a smaller amplitude.
Total internal reflection is the phenomenon that occurs when light passes from a medium with a higher refractive index to a medium with a lower refractive index at an angle greater than the critical angle. The critical angle is the angle of incidence at which the light ray is totally reflected back into the first medium. Total internal reflection can be used to create optical fibers, which are used in telecommunications and other applications.
Optical instruments are devices that use light to create images. Some common optical instruments include telescopes, microscopes, and cameras. Telescopes are used to magnify distant objects, microscopes are used to magnify small objects, and cameras are used to capture images of objects.
Ray optics is a useful tool for understanding many optical phenomena. However, it is important to remember that it is a simplified model of light. Light is actually a wave, and the wave nature of light can lead to phenomena that cannot be explained by ray optics. For example, diffraction and interference are phenomena that can only be explained by considering the wave nature of light.
What is the difference between a ray and a beam of light?
A ray is a line that represents the path of light. A beam of light is a group of rays that travel in the same direction.
What is the law of reflection?
The law of reflection states that the angle of incidence is equal to the angle of reflection. The angle of incidence is the angle between the incident ray and the normal, which is a line perpendicular to the reflecting surface. The angle of reflection is the angle between the reflected ray and the normal.
What is the law of refraction?
The law of refraction states that when light passes from one medium to another, it bends. The amount of bending depends on the refractive indices of the two media. The refractive index of a medium is a measure of how much light bends when it passes from air into that medium.
What is total internal reflection?
Total internal reflection is the phenomenon that occurs when light passes from a medium with a higher refractive index to a medium with a lower refractive index, and the angle of incidence is greater than the critical angle. The critical angle is the angle of incidence at which the light ray is refracted so that it travels parallel to the boundary between the two media.
What is a prism?
A prism is a transparent object with two flat, parallel surfaces and two curved surfaces. The curved surfaces are called the bases of the prism. The flat surfaces are called the faces of the prism. When light passes through a prism, it is refracted by the two faces of the prism. The amount of refraction depends on the angle of incidence and the refractive indices of the two media.
What is a lens?
A lens is a transparent object that can bend light. Lenses are used in many different applications, such as eyeglasses, cameras, and microscopes. There are two main types of lenses: converging lenses and diverging lenses. Converging lenses are thicker in the middle than they are at the edges. They bend light rays so that they converge at a point called the focal point. Diverging lenses are thinner in the middle than they are at the edges. They bend light rays so that they diverge, or spread out.
What is a mirror?
A mirror is a surface that reflects light. Mirrors are used in many different applications, such as mirrors in bathrooms, mirrors in cars, and mirrors in telescopes. There are two main types of mirrors: plane mirrors and curved mirrors. Plane mirrors are flat. Curved mirrors can be concave or convex. Concave mirrors are curved inward. Convex mirrors are curved outward.
What is a rainbow?
A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth’s Atmosphere. Rainbows can be full circles. However, the observer normally sees only an arc formed by illuminated droplets above the ground, and centered on a line from the Sun to the observer’s eye.
What is a mirage?
A mirage is an optical illusion that causes an image of distant objects to appear displaced from their true position. Mirages are most commonly seen in hot, dry areas, such as deserts. They can also be seen on hot roads and in the Arctic. There are two main types of mirages: inferior mirages and superior mirages. Inferior mirages are the most common type of mirage. They occur when light travels from a hot, dry area to a cooler, moist area. The light bends as it passes through the different layers of air, and this causes the image of an object to appear to be floating above the ground. Superior mirages are less common than inferior mirages. They occur when light travels from a cool, moist area to a warmer, drier area. The light bends as it passes through the different layers of air, and this causes the image of an object to appear to be sinking below the ground.
What is a halo?
A halo is a ring of light that appears around the Sun or Moon. Halos are caused by the refraction and reflection of light by ice crystals in the atmosphere. There are many different types of halos, but the most common type is the 22-degree halo. The 22-degree halo is a ring of light that is 22 degrees in diameter. It is caused by the Refraction Of Light by ice crystals that are hexagonal in shape.
What is a sun dog?
A sun dog is a bright spot of light that appears on either side of the Sun. Sun dogs are caused by the refraction and reflection of light by ice crystals in the atmosphere. Sun dogs are most commonly seen in the Arctic and Antarctic, but they can also be seen in other parts of the world.
**What is a corona?
A ray of light traveling from air to water is refracted. Which of the following is true?
(A) The light bends towards the normal.
(B) The light bends away from the normal.
(C) The light bends at the same angle as it entered the water.
(D) The light bends at a 90 degree angle.A ray of light traveling from water to air is refracted. Which of the following is true?
(A) The light bends towards the normal.
(B) The light bends away from the normal.
(C) The light bends at the same angle as it entered the water.
(D) The light bends at a 90 degree angle.A convex lens is used to focus light. Which of the following is true?
(A) The light rays are bent towards the center of the lens.
(B) The light rays are bent away from the center of the lens.
(C) The light rays are bent parallel to each other.
(D) The light rays are bent at a 90 degree angle.A concave lens is used to spread light. Which of the following is true?
(A) The light rays are bent towards the center of the lens.
(B) The light rays are bent away from the center of the lens.
(C) The light rays are bent parallel to each other.
(D) The light rays are bent at a 90 degree angle.A periscope is used to see around corners. Which of the following is true?
(A) It uses two mirrors to reflect light.
(B) It uses two lenses to refract light.
(C) It uses a combination of mirrors and lenses to reflect and refract light.
(D) It uses a combination of mirrors and prisms to reflect and refract light.A Microscope is used to magnify small objects. Which of the following is true?
(A) It uses two convex lenses to focus light.
(B) It uses two concave lenses to focus light.
(C) It uses a combination of convex and concave lenses to focus light.
(D) It uses a combination of mirrors and lenses to focus light.A Telescope is used to see distant objects. Which of the following is true?
(A) It uses two convex lenses to focus light.
(B) It uses two concave lenses to focus light.
(C) It uses a combination of convex and concave lenses to focus light.
(D) It uses a combination of mirrors and lenses to focus light.A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth’s atmosphere. It takes the form of a multicoloured arc. Rainbows can be full circles. However, the observer normally sees only an arc formed by illuminated droplets above the ground, and centered on a line from the Sun to the observer’s eye.
Which of the following is true about rainbows?
(A) Rainbows are caused by the refraction of light by water droplets in the atmosphere.
(B) Rainbows are caused by the reflection of light by water droplets in the atmosphere.
(C) Rainbows are caused by the diffraction of light by water droplets in the atmosphere.
(D) Rainbows are caused by the scattering of light by water droplets in the atmosphere.A mirage is an optical illusion that causes an image of distant objects to appear displaced from their true position. It is most commonly seen in hot, dry regions, and can be caused by the refraction of light by layers of air of different temperatures.
Which of the following is true about mirages?
(A) Mirages are caused by the refraction of light by water droplets in the atmosphere.
(B) Mirages are caused by the reflection of light by water droplets in the atmosphere.
(C) Mirages are caused by the diffraction of light by water droplets in the atmosphere.
(D) Mirages are caused by the scattering of light by water droplets in the atmosphere.A lens is a piece of transparent material, usually glass, that is used to bend light. Lenses are used in a variety of optical instruments, such as cameras, telescopes, and microscopes.
Which of the following is true about lenses?
(A) Lenses can be used to focus light.
(B) Lenses can be used to spread light.
(C) Lenses can be used to reflect light.
(D) Lenses can be used to refract light.