The radius of curvature of a converging mirror is 30 cm. At what distance from the mirror should an object be placed so as to obtain a virtual image?
(a) infinity
(b) 30 cm
(c) Between 16 cm and 30 cm
(d) Between 0 cm and 15 cm
1 Answers
Talk Doctor Online in Bissoy App
A small spherical steel ball is placed a little away from the centre of a large concave mirror of radius of curvature 2.5 m, if the ball is released,
Correct Answer - C `T=2pisqrt((R)/(g))=2pisqrt((2.5)/(10))=(2pixx5)/(10)=pis`
2 Answers 1 views
A convex mirror has radius of curvature of 20 cm. An object is placed at such a distance from the mirror that the size of image is exactly half that o
Correct Answer - C f=10 , `m=f/(f-u)` `m=1/2 rArr u=-10`
2 Answers 1 views
A small candle 2.5 cm in size is placed 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a scr
(a) Using the relation, `(1)/(u)+(1)/(v)=(1)/(f)` `(1)/(v)=(1)/(f)-(1)/(u)=(1)/(-18)=(1)/((-27))` v=-54cm The negative sign shows that the image is formed in front of the mirror, i.e., on the side of the object itself. Thus,...
2 Answers 1 views
A concave mirror has a radius of curvature of 24 cm. How far is an object from the mirror, if an image is formed that is (i) virtual and 3.0 times the
Given,R=-24 cm Hence, `f=R/2=-12 cm` (i) image is virtual and three times larger. Hence, u is negative and v is positive. Simultaneousely, `abs(v)=3abs(u)`. So let, u=-x then, v=+3x Substituting in...
2 Answers 1 views
Two thin converging lenses are placed on a common axis, so that the centre of one of them coincides with the focus of the other. An object is placed a
Here,`f_(1)=+5.0 cm and f_(2)=-10.0 cm` Therefore, the combined focal length F is given by `1/F=1/(f_(1))+1/(f_(2))=1/5.0-1/10.0=+1/10.0` `therefore` F=+b10.0 cm i.e., the combination behaves as a converging lens of focal length 10.0...
2 Answers 1 views
An object 5 cm tall is placed 1 m from a concave spherical mirror which has a radius of curvature of 20 cm. The size of the image is
Correct Answer - C (c ) We have, `I/O=f/((f-u))` `rArr I/5=(-10)/(-10-(-100))` Size of the image , I=0.55 cm
2 Answers 1 views
Assertion In front of a concave mirror, a point object is placed between focus and centre of curvature. If a glass slab is placed between object and m
Correct Answer - C (c) Glass slab will shift the object towards mirror. If it comes between pole and focus the image will become virtual.
2 Answers 3 views
A convex lens of radii of curvature 20cm and 30 cm respectively. It is silvered at the surface which has smaller radius of curvature. Then it will beh
Correct Answer - B Focal length for lens, `1/(f_(L)) = (mu_(g) - 1) (1/(R_(1)) - (1)/(R_(2)))` Here `mu_(g) = 1.5, R_(1) = 20 cm, R_(2) = -30 cm` `:. (1)/(f_(L)) =...
2 Answers 1 views
Assertion : The radius of curvature of a mirror is double of the focal length. Reason : A concave mirror of focal length f in air is used in a medium
Correct Answer - C Focal length of a mirror does not depend on the medium in which mirror is held. It depend on the radius of the sphere from which it...
2 Answers 3 views
Two identical thin converging lenses brought in contact so that their axes coincides are placed `12.5cm` form an object. What is the optical power of
Correct Answer - `10D`, Optical pwer of each lens `= 5D` `u = -12.5cm, m = (v)/(u) = -4, rArr v = +50` Alsor, `(1)/(f) = (1)/(v) - (1)/(u) rArr =...
2 Answers 1 views