Question

A hair dresser stands with her nose 20 cm in front of a plane mirror for what distance must she focus her eyes in order to see her nose in the mirror?

Solution

Correct option is

40 cm

 

   

                      

Distance from mirror = 20 × 2 = 40 cm.

SIMILAR QUESTIONS

Q1

A particle moves towards a concave mirror of focal length 30 cm along its axis and with a constant speed of 4 cm/ sec. What is the speed of its image when the particle is at 90 cm from the mirror?

Q2

A thin flat glass plate is placed in front of a convex mirror. At what distance b from the plate should a point source of light S be placed so that its image produced by the rays reflected from the front surface of the plate coincides with the image formed by the rays reflected from the mirror? The focal length of the mirror is f = 20 cm and the distance from the plate to the mirror a = 5 cm. How can the coincidence of the images be established by direct observation

                                                                                                                                     

Q3

 

A screen S is placed a distance b = 5 cm from a circular convex mirror as shown in figure. An object RP of height h = 3 cm is arranged a distance a = 5 cm from the screen. Where must an observer position himself to see the image of the entire object? What are the maximum dimensions of the object (with the given arrangement of the object, the mirror and the screen) for the mirror to reproduce and image of the entire object? The diameter of the mirror is d = 10cm.

                                                                            

 

                                                                     

Q4

A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm. the image will form at                                                                                          

Q5

Figure shows two rays A and B being reflected by a mirror and going as A` and B`. The mirror

                                                                              

Q6

Figure shows three transparent media of refractive indices µ1, µ2 and µ3. A point object O is placed in the medium µ2. If the entire medium on the right of the spherical surface has refractive index µ1, the image forms at O`. If this entire medium has refractive index µ3, the image forms at O``. In the situation shown, 

                                                                                

Q7

An object of length 2.5 cm is placed at a distance of 1.5f from a concave mirror where f is the magnitude of the focal length of the mirror. The length of the object is perpendicular to the principal axis. Find the length of the image. Is the image erect or inverted?

                                                                                                   

Q8

A convex mirror has its radius of curvature 20 cm. Find the position of the image of an object placed at a distance of 12 cm from the mirror.

                                                                                            

Q9

which mirror should a boy use, if he stands straight in front of a mirror at a distance of 30cm away from it and sees his erect image whose height is 1/6 th of his real height, is

Q10

An object of height 5 cm is placed in midway between a concave mirror of radius of curvature 30 cm and a convex mirror of radius of curvature 30 cm. The mirrors are placed opposite to each other and are 60 cm apart. The position of the image formed by reflection at convex mirror is.