Reflection of Light Important Questions

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Very Short Answers Questions [1 Mark Questions]

Ques. Which statement is true for the reflection of light?

1. The reflected light is less bright than the incident light.
2. The sum of the angle of incidence and reflection is always greater than 90°.
3. The angle of incidence and reflection are equal.
4. The beams of the incident light, after reflection, diverge at unequal angles.

Ans. The correct answer is c. The angle of incidence and reflection are equal.

Explanation: According to the laws of reflection, the angle of incidence is equal to the angle of reflection.

Ques. A beam of light incident on a plane mirror forms a real image on reflection. The incident beam is

1. Divergent
2. Convergent
3. Parallel
4. None of the above

Ans. The correct answer is b. Convergent

Explanation: On reflection, a light beam incident on a plane mirror produces a convergent beam. This is because the plane mirror reflects all of the incident light rays at the same angle. This means that the reflected light rays focus behind the mirror to produce a real image.

Ques. The brilliance of a diamond is due to

1. Total internal reflection
2. Reflection
3. Diffraction
4. Refraction

Ans. The correct answer is a. Total internal reflection

Explanation: The total internal reflection of light within the diamond is the main cause of its brilliance.

Ques. The image formed by a convex spherical mirror is

1. Inverted
2. Virtual
3. Real
4. Enlarged

Ans. The correct answer is b. Virtual

Explanation: The image formed by a convex spherical mirror is virtual, erect, and diminished.

Ques. What causes haloes (rings) around the sun or the moon?

1. Total internal reflection
2. Dispersion
3. Reflection of light
4. Refraction of light

Ans. The correct answer is c. Reflection of light

Explanation: Haloes, or rings, are seen when the sun or moon is seen through a thin veil of high clouds. These are generated as a result of light reflection by icy crystals in the atmosphere.

Ques. What is an image?

Ans. An image is the point at which light rays from an object meet or appear to meet after reflection or refraction.

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Short Answers Questions [2 Marks Questions]

Ques. If a ray of light incident on a smooth horizontal surface at an angle of 35^o with the normal. Find the angle of reflection.

Ans. Given, the angle of incidence, ∠i = 35^o

According to the law of reflection, we have

∠i = ∠r

Where ∠r is the angle of reflection.

Therefore, the angle of reflection is 35^o

Ques. Explain the laws of reflection.

Ans. According to the laws of reflection

1. The incident ray, the reflected ray, and the normal to the reflecting surface all lie in the same plane, called planar of incidence.
2. The angle of incidence is equal to the angle of reflection.

∠i = ∠r

Ques. Why is a real image always inverted?

Ans. When the light beams converge, a real image is formed. Real images are always formed below the principal axis and therefore inverted, whereas virtual images are always generated over the principal axis and so erect.

Ques. Explain the total internal reflection.

Ans. Total internal reflection is the phenomenon in which waves arriving at the interface from one medium to another are entirely reflected back into the first medium rather than refracted into the second medium.

Ques. What are the conditions for the occurrence of total internal reflection?

Ans. The conditions for the occurrence of total internal reflection are

• The light must travel from denser to rarer medium.
• The angle of incidence must be greater than the critical angle for the given pair of media.

Ques. What is light?

Ans. The visible part of the electromagnetic spectrum that produces the sensation of sight in our eyes is known as the light. Light is a form of energy.

Ques. What is the reflection of light?

Ans. The phenomenon of bouncing back of light in the same medium when the light falls on a smooth surface is known as the reflection of light.

Ques. Define refraction of light.

Ans. The phenomenon of change in the direction of the path of light when it goes from one medium to another medium is called the refraction of light.

Ques. What is Ray optics?

Ans. Ray optics, commonly referred to as geometrical optics, is an optics model that defines light propagation in terms of rays. In ray optics, a ray is a helpful abstraction for estimating the paths along which light propagates under particular conditions.

Ques. What is meant by a mirror?

Ans. A mirror is an optical device that reflects light that strikes it. It is used to see object images. There are several types of mirrors, each with its unique function. The mirror is essentially a piece of transparent glass having two sides, one of which is coated with a reflecting substance and the other for reflection.

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Long Answers Questions [3 Marks Questions]

Ques. The glancing angle of a ray of light incident on a smooth surface is 55^o. What is the value reflecting angle?

Ans. We know, the glancing angle is the angle between the reflecting surface and the incident ray.

Given, the glancing angle = 55^o

Then, the angle of incidence = 90 - 55 = 35^o

According to the law of reflection, we have

∠i = ∠r

Where ∠r is the angle of reflection.

Therefore, the angle of reflection is 35^o

Ques. What are the different types of reflection?

Ans. There are two types of reflection. These are

• Specular reflection: Specular reflection occurs when a parallel beam of incident light bounces back and maintains its parallel alignment after reflection from the surface. This is only possible if the reflecting surface is extremely smooth or well-polished. It is often referred to as regular reflection.

• Diffuse reflection: When a parallel beam of incident light after reflection from a surface is scattered in several directions rather than just one, this is referred to as diffuse reflection. Diffusion reflection takes place when the reflecting surface is rough or uneven. It is often referred to as irregular reflection.

Ques. What is meant by multiple reflections?

Ans. When light beams reflect off a mirror, they produce images. When two mirrors are placed parallel to each other, they create an infinite number of images along a straight line. 

• When two mirrors are placed at an angle to each other above a circle, countless images of the circle appear between the mirrors. 
• The center of the circle is located at the imaginary intersection of the two mirrors. When four mirrors are arranged in a square with their reflective surfaces facing each other, they create an infinite number of images in a plane. 
• Similarly, when four mirrors are arranged in a pyramid shape, with each pair of mirrors angled towards each other and placed above a sphere, they create numerous images of the sphere. 
• If the base of the pyramid is rectangular, the images will spread over a region of a torus.

Ques. What is the principle behind the working of a mirror?

Ans. When light hits a reflective surface, it bounces back. 

• Light is energy, and energy can either be reflected or absorbed. 
• Mirrors reflect light energy because they are smooth at a microscopic level. 
• When light hits a rough surface, it bounces back in all directions, which is called diffuse reflection. 
• When light hits a smooth surface, it bounces back in one direction, which is called specular reflection.

Ques. What are the properties of light?

Ans. The following are the properties of light

• Reflection: It is the phenomenon of bouncing back of light to the same medium when it strikes a smooth surface.
• Refraction: The phenomenon of bending of light while traveling from one medium to another.
• Dispersion: The splitting of white light into its constituent colors is known as dispersion.
• Diffraction: It is the bending of light around the corners of an obstacle.

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Very Long Answers Questions [5 Marks Questions]

Ques. What are the differences between reflection and refraction?

Ans. The following are the differences between reflection and refraction

Ques. What are the applications of the reflection of light in daily life?

Ans. The following are the applications of the reflection of light in daily life

• The wing and rear-view mirrors of a car are formed of convex and plane mirrors, respectively. The driver can see objects on both sides of the car through the two wing mirrors. The rear-view mirror allows the driver to see what is behind the vehicle.
• The mirror image produced by a home mirror is the best example of specular reflection that we see in our daily lives.
• Ammeters and voltmeters use mirrors to avoid parallax errors. The reading is obtained at a position where the image of the pointer is directly under the pointer.
• A mirror in a microscope is used to reflect light to the specimen under the microscope.
• To gather dim light from distant stars, an astronomical reflecting telescope uses a huge parabolic mirror. To reflect the image to the eyepiece, a plane mirror is used.
• Torches and car headlights use parabolic mirrors as reflectors. A small bulb is placed at the mirror's focus point to create parallel beams.

Ques. What are the applications of total internal reflection?

Ans. The following are the applications of total internal reflection

• Optical fibers: It is used in optical fibers to transmit light signals over long distances with very little loss. Optical fibers are used in telecommunications, computer networks, and other applications.
• Prisms: It is used in prisms to refract and disperse light. Prisms are used in binoculars, telescopes, and other optical instruments.
• Periscopes: It is used in periscopes to allow people to see over obstacles. Periscopes are used in submarines, tanks, and other military vehicles.
• Night vision goggles: It is used in night vision goggles to amplify low levels of light. Night vision goggles are used by militaries and law enforcement agencies.
• Medical imaging: It is used in medical imaging devices such as endoscopes and optical coherence tomography (OCT). Endoscopes are used to examine the inside of the body, while OCT is used to image the retina of the eye.

Ques. Explain the concept of virtual images and real images.

Ans. The image location is the point in space where every reflected light ray seems to diverge or out from. 

• Because the reflected light beams appear to diverge from this point, anybody viewing this image will believe that the actual body is located behind the reflecting surface. 
• The concept of the virtual image and the real image arises here. 
• When light beams from a single source diverge or spread out after passing through an optical lens or being reflected, a virtual image is formed. 
• Virtual images are produced when they appear to diverge, but because they never really converge, they cannot be cast onto a screen like a projector screen. 
• Real images, on the other hand, are formed when the light beams from the reflected light converge or meet at a single point on the later side of the lens. 
• Because the light beams are converging, this indicates the images being created actually exist. 
• In contrast to virtual images, if a projection screen is placed in the path of a real image, the image will be produced on the screen. 
• The projectors in the cinema theatres generate real images. 
• Real images arise when light beams converge, while virtual images appear when light beams appear to combine.

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