When a concave mirror is placed facing the sun the sun's rays converse to a point 10 cm from the mirror now an erect 2 cm long pin placed 15 CM Away on the principal axis of the mirror if you want to get the image of the pin on a card would you place the card what would be the nature and the height of the image
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We know when light ray comes from infinite distance ( or very far distance ) strike into mirror then they converge to a point known as focus. and distance of focus to pole of mirror is known as focal length .
hence ,
focal length of mirror = -10 cm { focal length negative due to concave mirror }
now,
use mirror formula,
1/v + 1/u =1/f
1/v + 1/(-20) = 1/(-10)
1/v = 1/20 - 1/10
v = -20 cm
hence position of image is also 20cm in side of object .
also ,
magnification = -v/u
= -(-20)/(-20)
= -1
hence,
magnification = -1
this implies that size of object is equal to size of image . and negative sign of magnification indicate image formed real and inverted
hence ,
focal length of mirror = -10 cm { focal length negative due to concave mirror }
now,
use mirror formula,
1/v + 1/u =1/f
1/v + 1/(-20) = 1/(-10)
1/v = 1/20 - 1/10
v = -20 cm
hence position of image is also 20cm in side of object .
also ,
magnification = -v/u
= -(-20)/(-20)
= -1
hence,
magnification = -1
this implies that size of object is equal to size of image . and negative sign of magnification indicate image formed real and inverted
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