Millikan's oil-drop experiment established that

Question

Accepted Answer

B. {'text': 'Electric charge is quantised in integer multiples of e', 'label': 'B'}

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: NCERT Class 12 Physics, Ch 11 "Dual Nature of Radiation and Matter", §11.1_

Answer

{'text': 'Electric charge is a continuously variable smooth quantity', 'label': 'A'}

Answer

{'text': 'The mass of the electron is one gram in ordinary units', 'label': 'C'}

Answer

{'text': 'Electrons carry no electric charge in an atomic system', 'label': 'D'}