Question

An object of size 8cm kept at 50cm from a concave mirror of focal length 30cm find the distance at which you should place on screen to obtain a clear image find nature and size of image
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Answer 1

Given :

• Object Height (Ho) = 8 cm
• Object Position (u) = - 50 cm
• Focal length (f) = - 30 cm
• Concave Mirror

To Find :

• Image position
• Image Size
• Image Nature

Solution :

Use mirror formula :

⇒1/f = 1/v + 1/u

⇒1/v = 1/f - 1/u

⇒1/v = 1/-30 - (1/-50)

⇒1/v = -1/30 + 1/50

⇒1/v = (-5 + 3)/150

⇒1/v = -2/150

⇒1/v = 150/-2

⇒1/v = -75

∴ Image is formed at distance of - 75 cm from mirror

$\rule{150}{2}$

⇒m = -v/u

⇒m = -(-75)/-50

⇒m = 75/50

⇒m = 1.5

$\rule{100}{2}$

⇒m = H'/Ho

⇒1.5 = H'/8

⇒H' = 1.5 * 8

⇒H' = 12