Physics Circle home Student Login

Home›Chapters›Ray Optics PYQs›Reflection & Mirrors›Question 12

JEE Main 2025 (28 Jan, Shift 2) · Reflection & Mirrors

Reflection & Mirrors question from JEE Main 2025 (28 Jan, Shift 2)

Q12JEE Main 2025 · 28 JAN · SHIFT 2Medium

Reflection & Mirrors

A concave mirror produces an image of an object such that the distance between the object and image is 20 cm. If the magnification of the image is –3, then the magnitude of the radius of curvature of the mirror is:

Show answer and solution

Answer: (b)

  1. m=−3⇒∣v∣=3∣u∣m = -3 \Rightarrow |v| = 3|u|, both real (in front).
  2. ∣v∣−∣u∣=2∣u∣=20⇒∣u∣=10 cm|v| - |u| = 2|u| = 20 \Rightarrow |u| = 10\text{ cm}, ∣v∣=30 cm|v| = 30\text{ cm}
  3. 1f=110+130=430⇒f=7.5 cm\frac{1}{f} = \frac{1}{10} + \frac{1}{30} = \frac{4}{30} \Rightarrow f = 7.5\text{ cm}
  4. R=2f=15 cmR = 2f = 15\text{ cm}. So the answer is (b) 15 cm.
Report a mistake

More questions on Reflection & Mirrors