12th Chapter 9 : Ray Optics 01 : Introduction & Reflection in a Plane Mirror JEE /NEET

Physics Wallah - Alakh Pandey・2 minutes read

Class 12 Physics covers Ray Optics, emphasizing reflection and refraction phenomena, with a focus on plane mirrors and image formation. The minimum mirror length needed to see a complete image is half the height of the object in front of it, enhancing the understanding of optics principles for image formation.

Insights

Ray Optics is a branch of optics that focuses on larger objects compared to the wavelength of light, dealing with phenomena like reflection and refraction. It includes understanding laws of reflection, normal incidence, and image formation by plane mirrors.
In image formation by a plane mirror, the image is virtual, upright, and equal in size to the object. The minimum length of a mirror to see a complete image from head to toe is half the height of the person. Understanding the relationship between the object, mirror, and image distances is crucial in determining the size and positioning of the image.

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What is the study of light called?
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Summary

00:00

"Mastering Ray Optics in Class 12"

Starting a new chapter in Class 12 Physics on Ray Optics, aiming to cover about 20 videos.
Ray Optics is an easy topic with practical questions that are scoring opportunities.
Emphasizing the importance of practicing questions and downloading assignments from www.physicswala.com.
The study of light is known as optics, with light being an electromagnetic wave in the visible region of the electromagnetic spectrum.
Light enables us to see objects, with its wavelength falling between 4000 to 8000 angstroms.
Optics is divided into Ray Optics (geometrical optics) and Wave Optics, with Ray Optics dealing with larger objects compared to the wavelength of light.
Ray Optics focuses on phenomena like reflection and refraction, with reflection in a plane mirror being the starting point.
Laws of reflection include the angle of incidence being equal to the angle of reflection, and all rays (incident, reflected, and normal) lying in the same plane.
Understanding reflection on spherical surfaces, ensuring the normal passes through the center for accurate angles of incidence and reflection.
Exploring normal incidence where the angle of incidence and reflection are both zero, indicating a special case in optics.

18:31

"Mirror Image Formation: Reflection and Distance"

Incident and normal rays are equal and both are zero angles.
Angle of incidence is zero, leading to an angle of reflection of zero.
Light reflects back in the same path if normal incidence occurs.
Image Formation by Plane Mirror involves creating a full dilaenge image.
The image is formed inside the mirror, not behind it.
The distance of the object from the mirror determines the image's distance.
A virtual image is formed in a plane mirror as the rays do not actually meet.
The line joining the object and image should be perpendicular to the mirror.
Making an image involves reflecting rays and ensuring they meet behind.
The process of creating an image involves extending the mirror and drawing perpendicular lines.

35:49

Mirror Image Formation and Properties Explained

The image will be formed by moving the mirror perpendicular to the object, reducing one in front of the object and extending the mirror.
Drawing the image perpendicular from the object, creating a right angle triangle with angles of 90 and 45 degrees.
The right angle triangle's hypotenuse rule will be √2, with both sides being 2.
The object is at a distance of √2 from the mirrored line, resulting in an image at the same distance.
To find the distance of the image, square both sides of the triangle and calculate the root, resulting in 2 cm below the object.
To determine the time in a mirror image, subtract the given time from 12:00, then subtract the given time from the result to find the mirror image time.
The minimum length of a mirror to see a complete image from head to toe is half the height of the person, denoted as H/2.
By creating a triangle with the object and its image, the ratio of sides in similar triangles is used to calculate the required mirror length.
The image in a plane mirror is virtual, upright, and the same size as the object.
The size of the object and image in a plane mirror is equal, with the image being upright and the same size as the object.

56:25

Mirror Length Determines Full Image Visibility

A man is standing between a ball of height capital H and a plane mirror, wanting to see the full image of the wall behind him.
The minimum length of mirror required for the boy to see the complete wall is h/3.
The distance between the wall and the mirror must be considered in the calculations.
The image of the wall is formed based on the distance of the object from the mirror.
The length of the mirror needed is determined by the distance of the object from the mirror.
The mirror length should be at least half the height of the person to see their full image.
The height of the mirror should be at least 1/2 of the height of the person and more to see the complete image.
The method involves calculating the distance of the object from the mirror to determine the mirror length.
The field of view of the object increases as you move away from it.
The question involves determining the maximum stretch or length a person can see the image of a point source of light in a mirror.

01:20:42

Light source affects object visibility and length.

When an object approaches a light source, it will stop seeing the lines or its image once it crosses the source, and vice versa. The object's visibility is affected by its position in relation to the light source.
To determine the length of a virtual object, consider the distance from D, the size of the object, and the positioning in relation to the light source. Understanding the principles of plane mirrors and their inclinations will help in comprehending image formation and the number of images produced.

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