Question

Identify the fundamental unit of electrical charge.

Short answer

The fundamental unit of electrical charge is the charge of an electron, \(-1.602 \times 10^{-19}\) coulombs.

Step-by-step solution

Identifying the Fundamental Unit

In the study of electricity, the fundamental unit of electrical charge is a basic, indivisible packet of charge. It is the charge possessed by a single electron or proton.

Understanding Historical Context

The discovery of the electron by J.J. Thomson in 1897 and subsequent experiments led to the understanding of electrical charge being quantized. Robert Millikan's oil-drop experiment later measured the charge of the electron, establishing the electron charge as a fundamental unit.

Defining the Quantitative Unit

The charge of an electron is mathematically defined as \(-1.602 \times 10^{-19}\) coulombs. Conversely, the charge of a proton is \(+1.602 \times 10^{-19}\) coulombs, making it equal in magnitude but opposite in sign to that of an electron.

Key concepts

Electron charge

The concept of electron charge represents one of the most fundamental elements in the field of physics and electrical engineering. An electron carries a negative charge, which is a basic and indivisible unit often referred to as the elementary charge. This makes it the smallest unit of charge that occurs in nature. Due to this, the electron charge acts as a fundamental measurement in various electrical applications and experiments.
In scientific terms, the charge of an electron is defined as \(-1.602 \times 10^{-19}\, \text{Coulombs}\). This tiny amount of charge is crucial because it gives rise to electric currents and fields when electrons interact with other charged particles. The charge of the electron is precisely equal in magnitude but opposite in sign to the charge of a proton, which carries a positive elementary charge. This balance is essential for the neutrality of atoms and the stability of matter.

Millikan oil-drop experiment

The Millikan oil-drop experiment is a landmark scientific experiment that played a pivotal role in measuring the electron charge accurately. Conducted by Robert A. Millikan in 1909, the experiment involved observing tiny oil droplets as they moved between two electrically charged plates. Millikan carefully controlled the voltage applied to the plates, adjusting it to suspend an oil drop in mid-air.
This groundbreaking approach allowed Millikan to calculate the charge on individual oil droplets, confirming that charge is quantized and comes in discrete amounts. By repeating the experiment with numerous droplets, he determined that all observed charges were multiples of the same smallest unit, confirming that the fundamental unit of charge is indeed the charge of a single electron. This experiment not only measured the electron charge but also provided crucial evidence supporting the theory of quantized electrical charge.

Quantization of electrical charge

Quantization of electrical charge is the principle that charge exists in discrete units or "quanta." This means that any charge observed in the universe is an integer multiple of the elementary charge, which is the charge of a single electron or proton. The idea of quantized charge arose from experimental observations and theoretical developments in the late 19th and early 20th centuries.
The concept implies that you won't find any fractional amount of charge; instead, every charge in nature is a whole number multiple of \(1.602 \times 10^{-19}\, \text{Coulombs}\). This theory is fundamental to our understanding of atomic and molecular structures. It suggests that charge can be created or destroyed by transferring electrons from one place to another, like in chemical reactions or electrical circuits. By acknowledging this quantization, scientists were able to predict and explain many electrical phenomena, further advancing technology and deepening our understanding of the universe.