All Exams Test series for 1 year @ ₹349 only
Question

An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. The magnification is:

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is
+0.6

To find the magnification of the object placed in front of a convex mirror, we can use the formula for magnification \( m \) in the context of mirrors:

\(m = \frac{h'}{h} = \frac{-v}{u}\)

where:

  • \( h' \) is the height of the image.
  • \( h \) is the height of the object.
  • \( v \) is the image distance.
  • \( u \) is the object distance (given as -10 cm since the object is on the left side of the mirror, according to the sign convention for mirrors).

For a convex mirror, the focal length \( f \) is positive. Given: \( f = 15 \, \text{cm} \) and \( u = -10 \, \text{cm} \).

Using the mirror formula,

\(\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\)

Substitute the values:

\(\frac{1}{15} = \frac{1}{v} + \frac{1}{-10}\)

Rearrange to solve for \( \frac{1}{v} \):

\(\frac{1}{v} = \frac{1}{15} + \frac{1}{10}\)

Calculate the right-hand side:

\(\frac{1}{v} = \frac{2}{30} + \frac{3}{30} = \frac{5}{30} = \frac{1}{6}\)

Therefore,

\(v = 6 \, \text{cm}\)

Now calculate the magnification \( m \):

\(m = \frac{-v}{u} = \frac{-6}{-10} = +0.6\)

Hence, the magnification of the object by the convex mirror is +0.6.

Let's validate the options given in the question:

  • +0.3 - Incorrect. This does not match the computed magnification.
  • +0.6 - Correct. This matches the computed magnification.
  • -0.3 - Incorrect. The sign is wrong and does not match the computed magnification.
  • -0.6 - Incorrect. The sign is wrong and does not match the computed magnification.
Was this answer helpful?

Similar Questions

  1. If an object is placed between infinity and the pole (P) in front of a convex mirror, what type of image will be formed?
  2. A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. Which option describes the image correctly?
  3. Which of the following mirrors is used by doctors to focus a parallel beam of light on the patient's organs like teeth for the examination?
  4. The radius of curvature of a spherical mirror is 20 cm. Its focal length is:
  5. The nature of the image formed by a concave mirror if the magnification produced by the mirror is +3 is:

Important Questions from Mirrors and Images

  1. Which one of the following telescopes contains only mirrors?

  2. The correct relation between the radius of curvature R and focal length f of a spherical mirror is

  3. Spherical mirror formula relating an object distance ‘u’, image distance ‘v’ and focal length of mirror ‘f’ may be applied to a plane mirror when

  4. The image of an object formed by a plane mirror is

  5. The image we see in plane mirror is

Need Expert Advice?
Upcoming Exams
RRB NTPC
September 27, 2026
Test Series
RRB ALP img
Railways
RRB ALP 2026 Mock Test series
1035 Tests 1 Tests Free
813 Attempts
4.3(234)
English, Hindi
More Questions from RRB ALP

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App