P as seen through the periscope. The mirrors are inclined at 45 degrees with the x-axis and eye is placed at the level y = -d .
21A trivial yet interesting son:
The rays meet the eye horizontally therefore we can easily say that the y co-ordinate is -d.
Now (the interesting part) for the x co-ordinate:
We know the image behaves like an apparent object.
Consider a light bulb as the object and that it is just switched on.
Light travels a distance of 4d before reaching the eye,but the light from the image should also take same time,and therefore travels same distance.
x co-ordinate =-d+4d=3d
Generally if the system consists of diff. mirrors inclined at diff. angles,You just need to fing the total distance travelled by light and trace that distance back along the final path of light to get the position of the image.
