Photoelectric effect

Photoelectric effect

Procedures

Measuring Planck's constant

Initial configuration

1. Cover the window of the Mercury Light Source Enclosure with the Mercury Lamp Cap. Cover the window of the Photodiode enclosure with the Photodiode Cap.
2. Adjust the distance between the Mercury Light Source enclosure and Photodiode enclosure so that the general spacing is between 30.0 cm to 40.0 cm. NOTE: The recommended distance is 35.0 cm.
3. On the Mercury Lamp Power Supply, press the button to turn on MERCURY LAMP. On the Tunable DC (Constant Voltage) Power Supply and DC Current Amplifier, push in the POWER button to the ON position.
4. Allow the light source and the apparatus to warm up for 10 minutes.
5. On the Tunable DC (Constant Voltage) Power Supply, set the Voltage Range switch to

$-4.5\,\mathrm{V}$ – $0\,\mathrm{V}$. On the DC Current Amplifier, turn the CURRENT RANGES switch to $10$-$13\,\mathrm{A}$.

1. On the DC Current Amplifier, push in the SIGNAL button to the “in” position for CALIBRATION.
2. Adjust the CURRENT RANGES knob until the ammeter shows that the current is zero.
3. Press the SIGNAL button so it moves to the “out” position for MEASURE.