Now, as we have already studied, when θ is very small, it can be ignored, and it is very close to the pole. Since θ is the incident angle, JK is perpendicular to the main axis, Therefore, CJ is perpendicular to the reflector at point J. Relation between the Focal Point (F) and Radius of Angle (R) of a Mirror Now, we will study how we can make the beam occur closer to the pole of the mirror and make it at a small inclination (negligible), and then the reflected light will converge and diverge at a certain point on the concave mirror and the convex mirror. For a better understanding, please consider the image below. If the height is measured in the upward direction perpendicular to the main axis, the height value is regarded as a positive value, and if the height is measured in the downward direction perpendicular to the main axis, the height value is regarded as a negative value. Similarly, if we measure the distance opposite to the direction of the incident light, the value of the distance is considered negative. The agreement is as follows: For DistanceĪssuming that if the distance is to be measured along the same incident light direction, the value of the distance is considered to be positive. According to the standard Cartesian notation convention, the pole is the only point where all distances can be calculated. In order to calculate the distance, to help us derive the relevant formulas for reflection and refraction, we adopted the notation convention. (b) Virtual image: If the image cannot be thrown onto the screen, but is formed on the other side of the mirror by the external extension of the light, the formed image is called a virtual image. In other words, if the image can be thrown onto the screen, it is a real image. (a) Real image: When the image and the mirror are formed on the same side, the image is called a real image. Read Also: Find focal length of concave lens using convex lens They are also used in street lamp reflectors. Concave mirrors are used in vehicles so that the driver knows that the vehicle is coming from behind. This is the focal point of the convex lens. If these reflected rays extend behind the mirror through the dotted line, they will meet at one point. Therefore, the convex mirror is also a divergent mirror. When parallel rays hit the mirror, they are reflected in a diffuse or divergent manner. Regardless of the distance between the subject and the mirrors, these mirrors are "always" virtual, upright and reduced. The convex mirror has a reflective surface that is curved outward. There are two types of spherical mirrors:Ĭoncave mirrors are also called converging mirrors, because in these types of mirrors, light rays converge at a point after impact and reflect back from the reflective surface of the mirror. Focal length: On the axis of the mirror, rays parallel to the axis converge after being reflected or refracted.Īlso Read: Ray Optics and Optical Instruments NCERT Solutions.Principal axis: It is an imaginary line which passes through the optical center and the center of curvature of the spherical mirror.Focal point: Any point where light rays parallel to the main axis converge after reflecting off the mirror.Pole (p): The pole is the midpoint of the mirror.Aperture: This is the point where light reflection actually occurs.Center of Curvature (r): The center of curvature of a spherical mirror is the point at the center of the mirror that passes through the curve of the mirror and has the same tangent and curvature at this point.Radius of curvature (c): It is the distance between the pole and the center of curvature.
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