plzz answer me friends
Answers
Answer:
Durham Cuban vixen bunch vixen Chico Hugh brunch check
Answer:
1).We prefer a convex mirror as a rear-view mirror in vehicles because it gives a wider field of view, which allows the driver to see most of the traffic behind him. Convex mirrors always form a virtual, erect, and diminished image of the objects placed in front of it.
2) CONCAVE MIRROR.
At the centre of curvature
The reason being, the image formed by a concave mirror is real, inverted and of the same size as the object. The position of the object must then be at the centre of curvature.
3).Aim
To determine the focal length of concave mirror by obtaining the image of a distant object.
Materials Required
A concave mirror, a mirror holder, a small screen fixed on a stand, a measuring scale and a distant object (a tree visible clearly through an open window).Theory/Principle
The spherical mirror with inward curved reflecting surface is called concave mirror. A beam of light generally converges after reflection from its surface, hence it is also called convergent mirror (Fig. 1).
cbse-class-10-science-lab-manual-focal-length-concave-mirror-convex-lens-1
Reflection by Concave Mirror
A concave mirror obeys the laws of reflection of light. In a concave mirror, rays of light are parallel to its principal axis and meet at a single point on the principal axis, after reflection from the mirror (as shown in Fig. 2). This point is the principal focus of the mirror.
The distance between the pole and principal focus of mirror is called, focal length of the mirror.
cbse-class-10-science-lab-manual-focal-length-concave-mirror-convex-lens-2
Image of Distant Object
When a parallel beam of light coming from a distant object, such as tree or pole is incident on the reflecting surface of a mirror, then after reflection, the rays converge at its principal focus as shown in the Fig. 3.
cbse-class-10-science-lab-manual-focal-length-concave-mirror-convex-lens-3
A distant object (at infinity) when reflected by a concave mirror, forms a real, diminished, and inverted image at the focus of the mirror.
As the distance between the pole 0 of the concave mirror and the focus F is the focal length of the concave mirror. Thus, the focal length of a concave mirror can be estimated by obtaining a real image of a distant object at its focus.
To obtain the position of image for a given object distance and focal length of a mirror, the following mirror formula can be used.
[latex]\frac { 1 }{ f } =\frac { 1 }{ v } +\frac { 1 }{ u }[/latex]
where, u = object distance,
v = image distance and f = focal length.
All u, v and f should be according to sign convention.
This expression is valid for concave as well as convex spherical mirrors.
Procedure
Fix a concave mirror in the mirror holder and place it on the table near an open window. Turn the face of mirror towards a distant object (suppose a tree).
Place the screen, fitted to a stand, infront of the concave mirror. Adjust the distance of screen, so that the image of the distant object is formed on it as given in the figure below. We can infer from the figure that a clear and bright image could be obtained if the distant object (a tree), is illuminated with sunlight and the screen is placed in the shade. A bright image of the Sun could also be obtained, if the sunlight is made to fall directly on the concave mirror.
When a sharp image of distant object is obtained, then mark the position of the centre of the stand holding the mirror and the screen as (a) and (b), respectively (see Fig. 4).
cbse-class-10-science-lab-manual-focal-length-concave-mirror-convex-lens-4
Measure the horizontal distance between the centre of the concave mirror and the screen with the help of a measuring scale.
Record the observations in the observation table.
Repeat the experiment two more times by obtaining the images of two different distant objects and measure the distance between the concave mirror and the screen in each case. Record them in the observation table.
Find the mean value of the focal length for all the observations for different objects.
Observations And Calculations
Least count of scale used = …………. mm = …………. cm
Focal length for first object (f1) = ………… m
Focal length for second object (f2) = ………….. m
Focal length for third object (f3) = …………. m
Mean focal length = [latex]\frac { { f }_{ 1 }+{ f }_{ 2 }+{ f }_{ 3 } }{ 3 = ………… m
