in a concave mirror of focal length 20cm on object is at a distance of 100cm find out position and nature of image
Answers
focal length of concave mirror, f = -20cm
object distance from the mirror, u = -100cm
using mirror formula,
1/v + 1/u = 1/f
⇒1/v + 1/-100 = 1/-20
⇒1/v - 1/100 = -1/20
⇒ 1/v = -1/20 + 1/100
⇒1/v = -5/100 + 1/100
⇒1/v = -4/100
⇒1/v = 1/-25
⇒ v = -25
hence, image distance from the mirror is 25cm.
magnification , m = -v/u = height of image /height of object
= -(-25cm)/(-100cm)
= -1/4
or, height of image = -1/4 × height of object.
so, it is clear that image is diminished and real.
Answer:
Explanation:
focal length of concave mirror, f = -20cm
object distance from the mirror, u = -100cm
using mirror formula,
1/v + 1/u = 1/f
⇒1/v + 1/-100 = 1/-20
⇒1/v - 1/100 = -1/20
⇒ 1/v = -1/20 + 1/100
⇒1/v = -5/100 + 1/100
⇒1/v = -4/100
⇒1/v = 1/-25
⇒ v = -25
hence, image distance from the mirror is 25cm.
magnification , m = -v/u = height of image /height of object
= -(-25cm)/(-100cm)
= -1/4
or, height of image = -1/4 × height of object.
so, it is clear that image is diminished and real.
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