✓ 4 MARKS
Case Study
🔥 APPEARED IN 3 BOARD SETS
A thin lens is a transparent optical medium bounded by two surfaces, at least one of which should be spherical. Applying the formula for image formation by a single spherical surface successively at the two surfaces of a lens, one can obtain the 'lens maker formula' and then the 'lens formula'. A lens has two foci -- called 'first focal point' and 'second focal point' of the lens, one on each side.
01 // VERIFIED BOARD OCCURRENCES
| Year | Paper Code | Set | Position |
|---|---|---|---|
| CBSE 2025 | Series 55-1 | Set 1 | Question 30 |
| CBSE 2025 | Series 55-1 | Set 2 | Question 29 |
| CBSE 2025 | Series 55-1 | Set 3 | Question 29 |
02 // OFFICIAL CBSE MARKING SCHEME BREAKDOWN
- Step 1: Stating the fundamental formula / law statement (+1 Mark)
- Step 2: Intermediate mathematical substitution or proof steps (+1 Mark)
- Step 3: Correct final value or conclusion with mandatory SI units (+1 Mark)