Physics · Refraction of light at plane and spherical surfaces, thin lens formula and lens maker formula

A concave spherical surface of radius of curvature separates two medium \& of re

A concave spherical surface of radius of curvature \( 10 \mathrm{cm} \) separates two medium \( \boldsymbol{x} \) \& \( \boldsymbol{y} \) of refractive index \( 4 / 3 \& \) \( 3 / 2 \) respectively. If the object is placed along principal axis in medium \( X \) then:

  • A. image is always real
  • B. image is real if the object distance is greater than 90 \( \mathrm{cm} \)
  • C. image is always virtual
  • D. image is virtual if the object distance is less than 90 \( \mathrm{cm} \)

Step-by-step solution

Using refraction formula for concave surface: n2/v - n1/u = (n2-n1)/R, with n1=4/3, n2=3/2, R=+10 cm (center on refracted side). Image distance v positive (real) when u > 80 cm. Hence for u > 90 cm, image is certainly real.
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