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QJEEM24Ph6f58: JEE Main 2024 Physics - Class 12 JEEM24Ph6f58 Solution: Light from a point source in air falls on a convex curved…

Light from a point source in air falls on a convex curved surface of radius 20 cm20 \mathrm{~cm} and refractive index 1.5. If the source is located at 100 cm100 \mathrm{~cm} from the convex surface, the image will be formed at ________ cm\mathrm{cm} from the object.

Step-by-Step Verified Solution

In the problem, you're dealing with refraction at a convex surface. The light is coming from a point source located in air (with a refractive index, μ1=1.0\mu_1 = 1.0 ) and entering a medium with a refractive index of μ2=1.5\mu_2 = 1.5 . The convex surface has a radius of curvature R=20 cmR = 20 \, \text{cm} , and the source is placed 100 cm100 \, \text{cm} from the convex surface.

The formula used to find the image distance vv due to refraction at a spherical surface is:

μ2v−μ1u=μ2−μ1R\frac{\mu_2}{v} - \frac{\mu_1}{u} = \frac{\mu_2 - \mu_1}{R}

Substituting the given values:

1.5v−1−100=1.5−120\frac{1.5}{v} - \frac{1}{-100} = \frac{1.5 - 1}{20}

This equation allows us to solve for vv , the distance from the convex surface to the image. Upon solving, we found that v=100 cmv = 100 \, \text{cm} , which means the image forms 100 cm100 \, \text{cm} on the other side of the convex surface, away from the point of refraction.

The distance from the object to the image isn't just vv , the distance from the surface to where the image forms. Since the object is 100 cm100 \, \text{cm} from the convex surface and the image also forms 100 cm100 \, \text{cm} from the convex surface but on the opposite side, the total distance between the object and the image is the sum of these distances:

  • Distance from the object to the convex surface: 100 cm100 \, \text{cm}
  • Distance from the convex surface to the image: 100 cm100 \, \text{cm}

Therefore, the total distance between the object and the image is 100 cm+100 cm=200 cm100 \, \text{cm} + 100 \, \text{cm} = 200 \, \text{cm} .

This calculation accounts for the physical layout where the object and the image are on opposite sides of the convex surface, and to determine the distance between them, you sum the distances from each to the surface. This results in the image being formed 200 cm200 \, \text{cm} from the object, which means if you were to measure directly from the object to its image, the total distance covered would be 200 cm200 \, \text{cm} .

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