Elementary charge on a proton What is the magnitude of electric charge carried by a single proton (i.e., the elementary positive charge)?

Introduction / Context:
The elementary charge e is a fundamental constant representing the magnitude of charge on a proton (positive) or equivalently the magnitude on an electron (negative). It is ubiquitous in electromagnetic theory, semiconductor physics, and circuit analysis involving charge transport and quantization.

Given Data / Assumptions:

• Proton carries +e; electron carries −e (same magnitude).
• Use SI units (coulombs).

Concept / Approach:

The accepted value of the elementary charge is approximately e = 1.602 × 10^-19 C; many problems use 1.6 × 10^-19 C for convenience. This constant underpins current definitions (e.g., the ampere is tied to fixed numerical value of e within the SI since 2019).

Step-by-Step Reasoning:

Verification / Alternative check:

Consistency checks include quantized Hall effect and single-electron tunneling experiments; all confirm the same elementary charge magnitude.

Why Other Options Are Wrong:

• 2.6 × 10^-19 C and 0.6 × 10^-19 C: incorrect magnitudes.
• 1.6 × 10^-13 C: wrong order of magnitude (too large by 10^6).
• 1.0 × 10^-19 C: not the accepted value.

Common Pitfalls:

Confusing the sign (proton positive, electron negative) or mixing in non-SI units; the question asks only for magnitude in coulombs.

Final Answer:

1.6 × 10^-19 C