A needle of height 4 cm is placed at a distance of 45 cm in front of concave lens of focal length 30 cm. The height of the image of the needle will be:

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RRB Group D 19 Sept 2022 Shift 3 Official Paper
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  1. 2.2 cm
  2. 1.6 cm
  3. 1.9 cm
  4. 2.5 cm

Answer (Detailed Solution Below)

Option 2 : 1.6 cm
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RRB Group D Full Test 1
100 Qs. 100 Marks 90 Mins

Detailed Solution

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The correct answer is 1.6cm.

Given:

 of a needle placed in a concave lens.

Formula:

Lens formula: 

Calculations:

Therefore,  for a concave lens.

Thus we have the height of needle is:

Therefore, the height of the image formed by the needle is 1.6cm.

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