RRB JE CBT-2 · 22 Apr 2025 · Shift 1 — Mathematics
RRB Junior Engineer (JE) · previous year paper
1 Mathematics questions from RRB JE CBT-2 · 22 Apr 2025 · Shift 1, with answers and Hindi and English explanations.
1.
एक बिंब को 25 cm फोकस दूरी के उत्तल लेंस के सामने 15 cm दूरी पर रखा गया है। प्रतिबिंब की दूरी ______ होगी।
An object is placed at a distance of 15 cm in front of a convex lens of focal length 25 cm. The image distance will be ______.
- (A)−9.37 cm
- (B)17.5 cm
- (C)−10.0 cm
- (D)−37.5 cm
Show answer and explanation
Answer: (D)
−37.5 cm
लेंस सूत्र 1/v − 1/u = 1/f, जहाँ u = −15 cm, f = +25 cm। 1/v = 1/25 − 1/15 = (3 − 5)/75 = −2/75। v = −37.5 cm (आभासी प्रतिबिंब, वस्तु की ओर)। अतः उत्तर −37.5 cm है।
Lens formula 1/v − 1/u = 1/f with u = −15 cm, f = +25 cm. 1/v = 1/25 − 1/15 = (3 − 5)/75 = −2/75. v = −37.5 cm (virtual image, same side as object). So the answer is −37.5 cm.
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