A concave mirror always forms a virtual image.
Q1. B) Answer the following questions in one sentence:
a) An object is placed at 20cm in front of a concave mirror of radius of curvature 20cm. State the
nature and size of the image relative to that of the object.
Ans:
b) What is a real image ?
Ans:
c) Write two uses of convex mirror.
Ans:
d) Write mirror formula.
Ans:
e) Define centre of curvature.
Ans:
f) How many images will be formed, if two plane mirrors are kept at an angle of 60 degree to each
other?
Ans:
g) Name the mirror which always forms a virtual image of the same size as that of the object. Ans:
Answers
Answer:
A) Given : Object distance, u=−20 cm
A concave mirror forms a real magnified image only when the image to be formed is inverted i.e. m=−3
Magnification m=
u
−v
∴ −3=
−20
−v
⟹v=−60 cm
Using mirror formula :
v
1
+
u
1
=
f
1
∴
−60
1
+
−20
1
=
f
1
⟹ f=
4
−60
=−15 cm
B)A real image is the collection of focus points actually made by converging rays, while a virtual image is the collection of focus points made by extensions of diverging rays. ... A real image occurs where rays converge, whereas a virtual image occurs where rays only appear to diverge
C) Two uses of convex mirror are: (i) It is used as a rear view mirror in vehicles. (ii) It is used as a vigilance mirror. (iii) it is used as a reflector in street lamps.
D) Let's explore the mirror formula (1/f = 1/v+1/u) and see how to locate images without drawing any ray diagrams.
E) the centre of a circle which passes through a curve at a given point and has the same tangent and curvature at that point.
F)Answer. 45 degeree=360/45 = 8-1=7 images. 60 degeree=360/60 = 6-1=5 image
G)Convex mirrors always form virtual images because the focal point and the centre of curvature of the convex mirror are imaginary points and that cannot be reached. So the image is formed inside the mirror and cannot be projected on a screen.