Refraction in a Rectangular Glass Block - Experiment Notes

Experiment Title

  • Title: Refraction in a Rectangular Glass Block

Apparatus

  • Thumb Pins: 4
  • Optical Pins: 4
  • Rectangular Glass Block: 1
  • Optical Board: 1
  • Plane Sheet of Paper: 1

Diagram

  • Ensure to include a diagram of the setup which includes the glass block and incident ray arrangement.

Procedure

  1. Setup:

    • Use thumb pins to hold the sheet of paper on the optical board.

  2. Measurement:

    • Measure and record the thickness of the glass block.

  3. Trace Glass Block:

    • Trace the outline (ABCD) of the glass block on the sheet of paper.

  4. Draw a Normal Line:

    • Remove the glass block and draw a normal line at point N where the incident ray strikes.

  5. Incident Ray:

    • Draw an incident ray making an angle of incidence i = 25^ ext{o} .
    • Fix two pins at points P1 and P2 on the incident ray.

  6. Replace Glass Block:

    • Place the glass block back and fix two other pins at P3 and P4 such that P3 and P4 are in a straight line with P1 and P2 when viewed from side DC of the block.

  7. Join Points:

    • Remove the block, join P3 and P4, and extend the line to meet line P1P2 at point N.

  8. Measure Length:

    • Measure length NM and denote it as L1.

  9. Repeat for Other Angles:

    • Repeat the experiment for angles of incidence: i = 35^ ext{o}, 45^ ext{o}, 55^ ext{o}, 65^ ext{o} .
    • In each case, determine corresponding values of L, L2, e, r, and ext{sin}^2i .

  10. Tabulate Readings:

    • Create a table to record the following:
      • Angle of Incidence (i°)
      • Length L0
      • Angle of Refraction (eo)
      • Length L
      • ext{sin}^2 i

Data Analysis

  • Graph Plotting:

    • Plot a graph of L2 against ext{sin}^2 i , starting both axes from the origin.

  • Calculate Slope and Intercept:

    • Determine the slope (M) of the graph and the intercept (C) on the vertical axis.

  • Extrapolate Values:

    • Use your graph to deduce the length (L) when i = 0^ ext{o} .
    • Evaluate constant K.

Graph Interpretation

  • Interpret the slope (M) obtained from the graph.
    • Explain what it signifies in the context of the experiment.

Precautions

  • Provide three key precautions taken during the experiment to ensure accuracy and reliability of results, such as:
    • Ensuring the glass block is placed properly each time without moving the pins.
    • Making precise angle measurements using a protractor.
    • Reducing parallax error when measuring distances or angles.

Conclusion

  • Summarize the findings and insights gained from analyzing the effect of refraction on the light ray as it passes through the glass block.