The charge of a single electron is approximately?

• A. 1.60 x 10^-18 coulombs
• B. 1.60 x 10^-19 coulombs
• C. 1.60 x 10^-20 coulombs
• D. 1.60 x 10^-21 coulombs

Answer: (B)

The charge of a single electron is the elementary charge, a fundamental constant in electricity. Its magnitude is about 1.60 × 10^-19 coulombs, with the electron carrying a negative sign, so its charge is -1.60 × 10^-19 C (the exact value is 1.602176634 × 10^-19 C, but 1.60 × 10^-19 C is the common approximate figure used in introductory problems). This small amount explains why individual electrons contribute tiny charges in circuits and electrostatic calculations, and why larger charges are often expressed in multiples of e rather than in raw coulombs. The provided numbers differ by factors of ten or more, so the value around 1.60 × 10^-19 C is the correct magnitude for a single electron.