All the rays, after reflection, from a concave mirror, meet at a point in front of the mirror. Name this point.
In an experiment to determine the focal length of concave mirror, the image of a distant object formed by a mirror is obtained on a screen. What distance is measured to estimate the focal length.
Which type of mirror is used to obtain a full length image of a distant tall building or tree?
Answers
Answer:
Determination Of Focal Length Of Concave Mirror And Convex Lens
Before getting started with the experiment, it is important to understand a few terms that are used in a concave mirror and convex lens:
Centre of curvature: For a curved mirror, the centre of curvature, C can be defined as the centre of a hollow glass sphere of which a curved mirror is a part.
Radius of curvature: For a curved mirror, the radius of curvature, R can be defined as the radius of the hollow glass sphere of a spherical mirror is part.
Principal axis: Principal axis is defined as the imaginary line passing through the pole and centre of curvature of the spherical mirror.
Principal focus: Principal focus is defined as a point at which the reflected rays meet or appear to meet for the spherical mirror. For a concave mirror, the principal focus is in the front and for a convex mirror, the principal focus is at the behind.
Below is an experiment to determine the focal length of a concave mirror and convex lens.
Aim
To determine the focal length of:
- Concave mirror
- Convex lens by obtaining the image of a distant object.
Theory
How to find focal length of concave mirror?
Following are the ways to obtain the focal length of the concave mirror:
- A concave mirror is defined as the spherical mirror whose reflecting surface is curved inwards and follows laws of reflection of light.
- The light rays coming from a distant object can be considered to be parallel to each other.
- If the image formed is real, inverted and very small in size, then the parallel rays of light meet the point in the front of the mirror.
- The image formed by the convex lens is real and can be obtained on the screen.
- f is used to denote the difference between the principal axis P and the focus F of the concave mirror.
How to find the focal length of convex lens?
Following are the ways to obtain the focal length of convex lens:
- The convex lens is thicker in the middle and thinner at the edges and is also known as the converging lens.
- The refracted rays from the parallel beam of light converge on the other side of the convex lens.
- If the image is obtained at the focus of the lens, the image would be real, inverted and very small.
- f is the focal length which is the difference between the optical centre of the lens and the principal focus.
- The image can be obtained on the screen as the image formed by the lens is real.
To determine focal length of a given concave mirror
Materials Required
- A concave mirror
- A measuring scale
- A screen holder
- A mirror holder
- A mirror stand
Procedure
The distance between the selected distinct object should be more than 50 ft.
The concave mirror placed on the mirror stand and the distant object should be facing each other.
The screen should be placed in front of the reflecting surface of the mirror. To obtain a clear, sharp image the screen should be adjusted.
Using a metre scale the distance between the concave mirror and screen can be determined. The distance is the same as the focal length of the given concave mirror.
Repeat the above procedure thrice to calculate the average focal length.
Answer:
The correct answer of this question is the focal length of Concave mirror and Convex lens by obtaining the image of a distant object.
Explanation:
Given - The rays after reflection from a concave mirror meet at a point in front of the mirror.
To Find - Name the point in experiment which determine the focal length of concave mirror.
Curved mirror the centre of curvature, C is defined as the centre of a hollow glass sphere, of which a curved mirror is a part.
Curved mirror the radius of curvature, R, can be defined as the radius of the hollow glass sphere of a spherical mirror.
Axis principal: The imaginary line passing through the pole and centre of curvature of the spherical mirror is defined as the principal axis.
For the spherical mirror, the principal focus is defined as the point at which the reflected rays meet or appear to meet. The primary focus of a concave mirror is in front, while the primary focus of a convex mirror is behind.
The focal length is measured Concave mirror , Convex lens by obtaining the image of a distant object.
A concave mirror is a spherical mirror with an inwardly curved reflecting surface that follows the laws of light reflection.
When the formed image is real, inverted, and very small in size, the parallel rays of light collide at the point in front of the mirror.
The image produced by the convex lens is real and can be seen on the screen.
The value f represents the difference between the principal axis P and the concave mirror's focus F.
Mirror which is used -
A concave mirror
A measuring scale
A screen holder
A mirror holder
A mirror stand
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