Please solve me for me i am totally confused. ??? :) ???
I. Prepare a project to investigate the relation between the ratio of output and input voltage
and number of turns in the secondary coil and primary coil of a self designed
transformer.
OR
Prepare a project to study various factors on which the internal resistance/cmf of a cell
depends.
II. Make a power point presentation explaining the total internal reflection with examples.
Questions:
(1) A concave mirror is placed in water. Will there be any change in its focal length?
Give reasons.
(2) A concave mirror of focal length 20 cm forms the image of an object which is
2 times the size of the object. Find the position of the object.
(3) An object 3 cm high is 25 cm from a concave mirror of focal length 20 cm.
Determine the position, size and nature of the image.
(4) Derive mirror formula for a concave mirror.
(5) A convex mirror of focal length 20 cm produces an image 1
5
th of the size of object.
What is the distance of the image from the mirror?
(6) Calculate the distance of an object of height h from a concave mirror of focal length
10 cm so as to obtain a real image of magnification.
(7) What type of mirror is used in search lights and head lights of vehicles and why?
(8) Which mirror is a convergent mirror? What type of image is formed by it? Can the
virtual image be screened or photographed?
(9) An object placed between the pole and focus of a concave mirror produces a virtual
and enlarged image. Explain using mirror formula.
(10) A concave mirror has radius of curvature of 40 cm. At what distance from the pole
of the mirror a parallel beam of light would be focused after reflection?
Here are the answers of some of your queries:
(1) No because the focal length is the property of the mirror, not of the medium in which it is placed and given by
Focal length = R / 2
(2)
f = -20cm(negative as concave mirror)
m= v/u = 2
so v = 2u (Positive as we know magnified image in concave mirror is always formed behind the mirror)
According to mirror formula
1/v + 1/u = 1/f
1/2u + 1/u = -1/20
u = -30cm
thus the position of the object is 40cm on the left of the concave mirror. Also the image would be enlarged, real and inverted.
(4) Please check the link given below for the derivation of mirror formula
Please Note:
u = (-)ve for both mirrors
f = (+)ve for Convex but (-)ve for Concave .
& finally , v = It depends upon the posion of object where it is placed :-
1.) In case of Concave Mirror , its generally (-)ve
2.) For Convex Mirror its generally (+)ve .
But when the object is placed between Focus & Pole of the mirrors , then the sign of v (Image Distance) changes
i.e. it becomes (-)ve for Convex & (+)ve for Concave Mirror.