Explain millikan's oil drop experiment in detail ?
Answers
Answer:
In 1909, Robert Millikan and Harvey Fletcher conducted the oil drop experiment to determine the charge of an electron. They suspended tiny charged droplets of oil between two metal electrodes by balancing downward gravitational force with upward drag and electric forces. The density of the oil was known, so Millikan and Fletcher could determine the droplets’ masses from their observed radii (since from the radii they could calculate the volume and thus, the mass). Using the known electric field and the values of gravity and mass, Millikan and Fletcher determined the charge on oil droplets in mechanical equilibrium. By repeating the experiment, they confirmed that the charges were all multiples of some fundamental value. They calculated this value to be 1.5924 × 10−19Coulombs (C), which is within 1% of the currently accepted value of 1.602176487 × 10−19 C. They proposed that this was the charge of a single electron.
Explanation:
Key Points
Millikan’s oil drop experiment measured the charge of an electron. Before this experiment, existence of subatomic particles was not universally accepted.
Millikan’s apparatus contained an electric field created between a parallel pair of metal plates, which were held apart by insulating material. Electrically charged oil droplets entered the electric field and were balanced between two plates by altering the field.
When the charged drops fell at a constant rate, the gravitational and electric forces on it were equal. Therefore, the charge on the oil drop was calculated using formula Q = [latex]\frac {m\cdot g}{E}[/latex] Millikan found that the charge of a single electron was 1.6 x 10-19 C.
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