Procedure for Real lab

 

1. Connections are made as shown in circuit diagram.
   
2. Insert key to start the experiment.
   
3. Adjust the rheostat value till the LED starts glowing, or in the case of the IR diode, whose light is not visible, until the ammeter indicates that current has begun to increase.
   
4. Corresponding voltage across the LED is measured using a voltmeter, which is the knee voltage.
   
5. Repeat, by changing the LED and note down the corresponding knee voltage.
   
6. Using the formula given, find the value of the Planck's constant.
   
   

Results
  Planck’s constant = ____________ Js.

Wavelength of IR LED = ____________ nm.