Which of the following best describes the evidence provided by the Millikan oil drop experiment?

• A. It demonstrated that electrons are embedded in a positively charged 'pudding'.
• B. It provided evidence for the existence of neutrons in the atom.
• C. It showed that atoms have a dense, positively charged nucleus.
• D. It measured the charge of the electron, confirming that charge is quantized.

Answer: (D)

Verified step by step guidance

1. Understand the historical context of the Millikan oil drop experiment, which was designed to measure the electric charge of a single electron.
2. Recognize that the experiment involved balancing the gravitational force and the electric force on tiny charged oil droplets suspended between two metal plates.
3. Use the balance of forces to calculate the charge on each oil droplet by applying the equation \(qE = mg\), where \(q\) is the charge, \(E\) is the electric field, \(m\) is the mass of the droplet, and \(g\) is the acceleration due to gravity.
4. Analyze the data from many droplets to find that the charges measured are always multiples of a smallest, fundamental charge, which corresponds to the charge of a single electron.
5. Conclude that this experiment provided strong evidence that electric charge is quantized and allowed the precise measurement of the electron's charge, rather than supporting models like the plum pudding or discovering neutrons or the nucleus.