Q2. Explain the process of image formation by concave mirror.
Answers
Answer:
When the object is between the centre of curvature (C) and the focus (F). When an object is placed in between the center of curvature and focus, the real image is formed behind the center of curvature. The size of the image is smaller as compared to that of the object.
Answer:Concave mirrors image formation Explanation:
In this lesson, we will discuss image formation in concave mirrors. However, before we delve into the topic let us quickly recall what a concave mirror is and the principles behind its working. A concave mirror is a type of spherical mirror in which, the reflecting surface is the inner curved surface of the sphere, i.e. in this type of mirrors the reflecting surface seems to be away from the incident light source. Because of their shape, the incident light is reflected inwards (converged), thus they are also called converging mirrors and they are used for focusing light.
Both laws of reflection are valid at every point on the curved surface of the mirror. The normal is drawn along the radius, i.e. it is drawn by joining the centre of curvature of the mirror to the point of incidence. The convergence of the rays after reflection is because the normal to the reflecting surface differs at each point on the mirror.
There is a formation of different images in a concave mirror. It mainly depends on the distance between the object and the mirror. Concave mirrors form both real and virtual images. When the concave mirror is placed very close to the object, a virtual and magnified image is obtained and if we increase the distance between the object and the mirror, the size of the image reduces and real images are formed. These real images can be projected on a screen. The focal point and the centre of curvature of the concave mirror lie in front of the mirror.
Important Terms
Pole: it is the centre of the reflecting surface of a spherical mirror. It lies on the surface of the mirror and it is usually denoted by P.
Centre of curvature: the centre of the sphere formed by the reflecting part of a spherical mirror is called centre of curvature. It is generally denoted by C. This is not a part of the mirror and it lies outside the reflecting surface of the mirror. For a concave mirror, it lies in front of the mirror.
The radius of curvature: it is the radius of the sphere formed by the reflecting part of the sphere. It is represented by R.
Principal axis: it is the straight line passing through the pole and centre of curvature of the spherical mirror. This is normal to the mirror at its pole.
Principal focus: the incident rays coming parallel to the principal axis after reflection appear to converge to a common point on the principal axis, this point is called the principal focus of a concave mirror. It is usually denoted by F.
Focal length: it is the distance between the pole and principal focus of the concave mirror. It is denoted by f.