Q12. A compound microscope has objective focal length 1 cm and eyepiece focal length 5 cm, with 20 cm separation. If final image is at the near point D = 25 cm, the exact magnitude of total angular magnification is:
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Q12. A compound microscope has objective focal length 1 cm and eyepiece focal length 5 cm, with 20 cm separation. If final image is at the near point D = 25 cm, the exact magnitude of total angular magnification is:

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G1 Physics · Accepted Answer

GIVEN: fₒ = 1 cm, fₑ = 5 cm, L = 20 cm, D = 25 cm; final image at near point. Step 1: Eyepiece forms a virtual image at vₑ = −25 cm. Let its object distance be uₑ = −s. Step 2: 1/5 = −1/25 + 1/s ⇒ 1/s = 1/5 + 1/25 = 6/25 ⇒ s = 25/6 cm. Step 3: Objective intermediate-image distance vₒ = L − s = 20 − 25/6 = 95/6 cm. Step 4: Objective linear magnification |mₒ| = vₒ/fₒ − 1 = 95/6 − 1 = 89/6. Step 5: Eyepiece near-point magnification mₑ = 1 + D/fₑ = 1 + 25/5 = 6. Step 6: |M| = (89/6) × 6 = 89. Do NO…