Practice portal › Electric Charge and Properties › Electric Charge and Coulomb's Law

If a body contains n₁ protons and n₂ electrons, the total amount of charge on the body is ______.

Asked in GSEB Board July 2021 · Properties of charge

• (1) (n₂ - n₁)e
• (2) (n₁ - n₂)e
• (3) (n₁ + n₂)e
• (4) (n₁ + n₂)e²

Step-by-step solution

Why the other options are wrong

• (1) This swaps the signs, treating the electrons as positive and the protons as negative. A body with more protons than electrons must be positive, but (n₂ - n₁)e would then come out negative.
• (3) This adds the magnitudes of the two kinds of charge. A proton and an electron carry opposite charges and cancel in pairs, so only the difference n₁ - n₂ survives.
• (4) This adds instead of subtracting, and squares e as well: e² has units C², so this cannot be a charge.

Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.