Procedure to run the simulation :

1. Click on "ENABLE POWER" button to start the experiment
   

   • This will activate all the circuit components and start the instruction panel
     

2. Click on "Place LED" button to place an LED on the canvas
   

   • You'll need to click on the canvas area to position the LED
     

3. Click on "Battery" button to place a battery on the canvas
   

   • Position the battery appropriately on the canvas
     

4. Click on "Ammeter" button to place an ammeter on the canvas
   

   • This will measure the current flow through the circuit
     

5. Click on "Voltmeter" button to place a voltmeter on the canvas
   

   • This will measure the voltage across the LED
     

6. Click on "Connect" button to connect the components
   

   • Click on the terminals of the components to create connections
     
   • Connect: Battery (+) → Ammeter → LED (+) → LED (-) → Battery (-)
     

7. Select LED Color from the dropdown menu
   

   • Choose from: Red, Blue, Green, or Yellow
     

8. Click "Click" button next to the color selection
   

   • This will enable the current measurement button
     

9. Click "Find Here" button to get the current value
   

   • This will show the current flowing through the LED
     

10. Use the voltage slider to adjust the voltage
    

    • Slide from 0 to 5V to find the threshold voltage where the LED just starts glowing
      

11. Observe the LED to determine the threshold voltage (V₀)
    

    • Note the voltage at which the LED first emits light
      

12. Record the data in the observations table
    

    • Enter the LED color, threshold voltage (V₀), and wavelength (λ) for each color
      

13. Repeat steps 2-12 for different LED colors (Red, Yellow, Green, Blue)
    

14. Click "Calculate Data" button after entering all observations
    

    • This will calculate 1/λ values for the graph
      

15. Click "Draw Graph" button to plot the graph
    

    • This will create a graph of V₀ vs 1/λ
      

16. Enter coordinates in the "Enter First Coordinate" and "Enter Second Coordinate" fields
    

    • Use two points from your graph to calculate the slope
      

17. Click "Find Slope" button to calculate the slope
    

    • This will give you the slope of the linear plot
      

18. Enter the calculated slope in the "Enter Slope" field
    

19. Click "Calculate" button to find Planck's constant
    

    • This will calculate h = (slope × e) / c
      
      

Procedure in Laboratory :

Apparatus :
A. 0-10 V power supply
B. Digital milliammeter
C. Digital voltmeter
D. Known wavelength LED’s (Light-Emitting Diodes).

Procedure in laboratory (diagram)






Procedure in laboratory :

Prepare a circuit as per follows




























Analysis :
A) Determine the Knee voltage for Red, Yellow, Green and Blue LEDs
B) Note down the wavelengths for Red, Yellow, Green and Blue LEDs
C) Calculate the value of Planck’s constant