Water

1. Determination of Refractive
Indices of Water and Transparent
Oil
Using a Plane Mirror, Equiconvex
Lens, and Adjustable Object Needle
Presented by: [Your Name]

2. Introduction
• This experiment involves determining the
refractive indices of water and transparent oil
using the apparent depth method. It helps in
understanding basic principles of optics and
refraction.

3. Objective
• To find the refractive indices of:
• (a) Water
• (b) Transparent oil
• using a plane mirror, equiconvex lens, and an
adjustable object needle.

4. Importance of Refractive Index
• The refractive index determines how much
light bends when it enters a medium. It is
crucial in designing lenses, optical
instruments, and for material identification.

5. Principle of Apparent Depth
• When an object is viewed through a
transparent medium, it appears closer due to
refraction. The apparent depth is less than the
real depth.

6. Formula Used
• Refractive index (n) = Real Depth / Apparent
Depth
• This relationship forms the basis of the
experiment.

7. Apparatus Required
• - Plane mirror
• - Equiconvex lens
• - Transparent liquids (water, oil)
• - Adjustable object needle
• - Retort stand
• - Scale or vernier calipers

8. Description of Equiconvex Lens
• An equiconvex lens has two outward-curving
surfaces. It is used here to hold the liquid and
allow focused observation of the image.

9. Setting Up the Apparatus
• Place the mirror flat on the table. The
equiconvex lens is positioned over it to form a
liquid container. The object needle is aligned
above.

10. Procedure - Part 1
• 1. Fill the lens with water.
• 2. Adjust the needle until its image aligns with
the actual tip (no parallax).
• 3. Measure the vertical distance from the
needle to the mirror.

11. Procedure - Part 2
• 4. Repeat the steps using transparent oil.
• 5. Record the apparent depth for both liquids.
• 6. Measure the real depth (thickness of the
liquid layer).

12. Observation Table Format
• Liquid | Real Depth (cm) | Apparent Depth
(cm) | Refractive Index
• -------|------------------|----------------------|----------
--------

13. Sample Observations
• Water: Real Depth = 2.5 cm, Apparent Depth =
1.9 cm, n = 2.5 / 1.9 ≈ 1.32
• Oil: Real Depth = 2.5 cm, Apparent Depth = 1.6
cm, n = 2.5 / 1.6 ≈ 1.56

14. Calculations
• Using the formula:
• n = Real Depth / Apparent Depth
• Compute n for each liquid using measured
values.

15. Sources of Error
• - Parallax errors
• - Imprecise measurement
• - Uneven liquid surface
• - Misalignment of needle and mirror

16. Precautions
• - Avoid shaking the table
• - Ensure needle is vertical
• - View needle from eye level to avoid parallax
• - Clean lens and mirror before use

17. Applications of the Experiment
• - Used in optical material identification
• - Understanding light propagation in tissues
(biosciences)
• - Relevant in ophthalmology and microscopy

18. Result
• Refractive Indices:
• - Water: Approximately 1.33
• - Transparent Oil: Approximately 1.56
• (Values vary slightly with temperature and
purity)

19. Conclusion
• The refractive indices of water and
transparent oil were determined using the
apparent depth method, confirming known
theoretical values.

20. Viva Questions & Answers
• Q1: What is refractive index?
• A: Ratio of real depth to apparent depth.
• Q2: Why is oil's refractive index higher than
water?
• A: Due to greater optical density.

21. Thank You
• Thank you for your attention!
• Questions and discussions are welcome.