Q15 of 45 Page 301

Compute the position of the object placed in front of a concave mirror of focal length ‘f’ so that the image formed is of the same size of the object.

Given,


Focal length= -f


(Because it is a concave mirror)


The magnification is given by



And the magnification is also given by



As the length of image (hi) =length of object (ho)


Hence, the magnification (m) =1


Therefore,



According to the mirror formula,






Hence, the object must be placed at double the focal length before the concave mirror.


More from this chapter

All 45 →
13

What is the magnetic field midway between two parallel conductors carrying same amount of current in the same direction and in the opposite direction?

 14

How can an AC generator be converted into a DC generator?

 1

Fill in the blanks

i) For a motor: a permanent magnet, then commercial motor: _______


ii) Focal length of a lens; metre, then for power of a lens____________


 2

Correct the mistakes, if any, in the following statements.

i) The magnetic field is a quantity that has magnitude only.


ii) Outside the bar magnet, the magnetic field lines emerge from the South Poleand merge at the North Pole.