SATHEE: Optics 3 Question 6

Optics 3 Question 6

6. What is the position and nature of image formed by lens combination shown in figure? (where, $f_{1}$ and $f_{2}$ are focal lengths)

(2019 Main, 12 Jan I)

(a) $\frac{20}{3} c m$ from point $B$ at right, real

(b) $70 c m$ from point $B$ at right, real

(d) $70 c m$ from point $B$ at left, virtual

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Answer:

Correct Answer: 6. (b)

Solution:

For lens $A$ , object distance, $u = - 20 c m$

Focal length, $f = + 5 c m$

From lens formula, $\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$

We have, $\frac{1}{v} = \frac{1}{5} - \frac{1}{20}$

$\frac{1}{v} = \frac{20 - 5}{20 \times 5} = \frac{15}{100}$

$v = \frac{20}{3} c m$

For lens $B$ , image of $A$ is object for $B$ .

$∴ u = \frac{20}{3} - 2 = + \frac{14}{3} c m$

$f = - 5 c m$

Now, from lens formula, we have

$\begin{aligned} \frac{1}{v} - \frac{1}{u} & = \frac{1}{f} \\ \frac{1}{v} & = \frac{1}{- 5} + \frac{3}{14} \\ \frac{1}{v} & = \frac{15 - 14}{5 \times 14} \\ v & = 70 c m \end{aligned}$

Hence, image is on right of lens $B$ and is real in nature.

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Optics 3 Question 6

6. What is the position and nature of image formed by lens combination shown in figure? (where, $f_{1}$ and $f_{2}$ are focal lengths)

Answer:

इंजीनियरिंग की तैयारी

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सदस्यता

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Optics 3 Question 6

6. What is the position and nature of image formed by lens combination shown in figure? (where, f1 and f2 are focal lengths)

Answer:

इंजीनियरिंग की तैयारी

चिकित्सा तैयारी

एनसीईआरटी पुस्तकें और समाधान

महत्वपूर्ण संसाधन

अन्य संसाधन

पाठ्यक्रम

परीक्षा मंच

नमूना मॉक टेस्ट

सदस्यता

एनसीईआरटी व्यायाम वीडियो समाधान

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6. What is the position and nature of image formed by lens combination shown in figure? (where, $f_{1}$ and $f_{2}$ are focal lengths)