Question

22. A convex lens of focal length 6 cm is held 4 cm from a newspaper
which has print 0.5cm. high by calculation determine the size and nature of the image produced.

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Answer 1

Question

A convex lens of focal length 6 cm is held 4 cm from a newspaper which has print 0.5cm. high by calculation determine the size and nature of the image produced.

Given

f = 6 cm

u = -4 cm

h1 = 0.5 cm

Solution

Lens formula: 1/v – 1/u = 1/f

1/V – 1/-4 = 1/6

1/V = 1/6 – 1/4 = (2 – 3)/12

V = -12 cm

m = v/u = h2/h1

-12/-4 = h2/0.5

h2 = 1.5 cm

Image is 1.5 cm high, virtual, erect and magnified.

$bts ❤ exo$

Answer 2

Answer:

➠ Focal length = 6cm

➠ u = -4cm

➠ h1= 0.5cm

lens formula = 1/v - 1/u = 1/f

$\frac{1}{v} - \frac{1}{ - 4} = \frac{1}{6} \\ \frac{1}{v} = \frac{1}{6} - \frac{1}{ - 4} \\ \frac{1}{v} = \frac{2 - 3}{12} \\ v = - 12$

$m = \frac{v}{u} = \frac{h2}{h1} \\ \frac{ - 12}{ - 4} = \frac{h2}{0.5} \\ h2 = 1.5$

∴Image is 1.5cm high , virtual , erect and magnified

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