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DSSSB TGT C10lensformula — practice questions

Explore 5 free C10lensformula questions in DSSSB TGT Physics. Open each question or exercise to read its content, reference answers and available explanation.

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C10lensformula questions and exercises with answers

Showing questions 1–5 of 5.

As per your syllabus, Physics, what is the LENS FORMULA?Read the answer and worked solution →As per your syllabus, what is the magnification (m) formula for a LENS — in terms of v and u?Read the answer and worked solution →As per your syllabus, a concave lens (f = −15 cm) forms an image at v = −10 cm. What is the object distance u?Read the answer and worked solution →As per your syllabus, for the same convex lens problem (f=+10, u=−15), what is the MAGNIFICATION?Read the answer and worked solution →As per your syllabus, what is 1 DIOPTRE — the SI unit of lens power?Read the answer and worked solution →

Worked practice questions

As per your syllabus, Physics, what is the LENS FORMULA?

  1. 1/v − 1/u = 1/f
  2. 1/v + 1/u = 1/f (this is the mirror formula)
  3. v + u = f
  4. v − u = f
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Correct answer: A. 1/v − 1/u = 1/f

As per your syllabus, Eq 9.8, lens formula = 1/v − 1/u = 1/f. Mirror formula has + sign.

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As per your syllabus, what is the magnification (m) formula for a LENS — in terms of v and u?

  1. m = h'/h = −v/u (this is for a mirror)
  2. m = h'/h = v/u
  3. m = u/v
  4. m = f/u
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Correct answer: B. m = h'/h = v/u

As per your syllabus, Eq 9.10, lens magnification m = v/u. Mirror magnification has the minus sign.

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As per your syllabus, a concave lens (f = −15 cm) forms an image at v = −10 cm. What is the object distance u?

  1. −10 cm
  2. +30 cm
  3. −30 cm
  4. +10 cm
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Correct answer: C. −30 cm

As per your syllabus, using lens formula: 1/u = 1/v − 1/f = 1/(−10) − 1/(−15) = (−3+2)/30 = −1/30 → u = −30 cm.

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