b) A bus driver looks into a plane mirror 20 cm long which is placed 50 cm in front of him. If the rear window is 500 cm away from the plane mirror, through what length of the rear window can he see whenever he looks into the mirror while he is driving?
Answers
Answer:
Two lamps, one rated 100W at 220V, and the other 60W at 220V, are connected in parallel to electric mains supply. What current is drawn from the line
Answer:
Explanation:
When viewed through the mirror the field of vision is said to be the area visible from the perspective of the observer .It actually depends on the visual angle at the the eye subtended by the two extreme points of the mirror. The field of vision increases with increase of visual angle
.
So it depends on followings
The position of with respect to the mirror
The distance of observers' eye from the mirror
The length of the mirror
The above figure explains the phenomenon of our problem
Where
M N ⇒ Mirror of length of 20 cm
E ⇒ Position of driver's eye
d = Distance from the center C of mirror MN = 50 c m
To get the field of vision when viewed through the mirror we are to draw the reflected rays coming to the eye of the observer being incident on two extreme points on the mirror , M and N as in our case .
Let at a distance of 500cm from the mirror the width of the field of vision be x , So the distance from point V will be (500+50)cm =550 cm
Now applying properties of similar triangle we can write
x/MN = 550/VC
⇒x/20 = 550/50
⇒ x = 20 x 11 = 220cm
