Procedure

Apparatus

Millikan’s oil drop apparatus, oil, DC supply.

Procedure for Simulation:

1. Click on the “START” button.
2. Click on the combo box to choose the oil.
3. Double click the “START” button of the stopwatch and note the time taken t₁ by a drop to travel distance l₁ between any two points.
4. Click “Voltage On” to suspend the same oil drop in air — this is the balancing voltage V.
5. Click the “X-Ray ON” button and note the time taken t₂ by the same drop to travel distance l₂ between any two points.
6. The charge of the drop is calculated using the equation:

$$q = \frac{6 \pi \eta r (v_1 + v_2) d}{V}$$

7. Repeat the experiment for another oil.

Observations