A lens is placed between a source of light and screen. It forms real image on screen for two different positions. If height of one image is 20 cm and the other is 80 cm, then the height of source of light (in cm) is_____.

A lens is placed between a source of light and screen. It forms real i

1.	A lens is placed between a source of light and screen. It forms real image on screen for two different positions. If height of one image is 20 cm and the other is 80 cm, then the height of source of light (in cm) is_____.
Answer» SOLUTION : LET height of source of light is `h_0`so for `1^(st)` magnification `\|m_1\| = \|(20)/(h_0)\|` And for `2^(nd)` magnification`\|m_2\| = \|(80)/(h_0)\|` We know thant `m_1m_2 = 1 ` so , `h_0 = 40 CM` . We know thatSo,

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A lens is placed between a source of light and screen. It forms real image on screen for two different positions. If height of one image is 20 cm and the other is 80 cm, then the height of source of light (in cm) is_____.

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