alleryMillikan's oil-drop experiment established that
AElectric charge is a continuously variable smooth quantity
BElectric charge is quantised in integer multiples of e
CThe mass of the electron is one gram in ordinary units
DElectrons carry no electric charge in an atomic system
Answer & Solution
Correct answer: B. Electric charge is quantised in integer multiples of e
1. Millikan (1913) measured charges on tiny oil droplets suspended by an electric field.
2. Every measured charge was an integer multiple of 1.602 × 10⁻¹⁹ C.
3. This proved that electric charge is quantised.
4. Combined with e/m, it enabled a precise electron mass measurement.
_Source: syllabus Physics, Ch 11 "Dual Nature of Radiation and Matter", §11.1_
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