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

Asked in GSEB Board March 2022 · Properties of charge

• (1) (n₂ + n₁)e
• (2) (n₁² + n₂²)e
• (3) (n₁² - n₂²)e
• (4) (n₂ - n₁)e

Step-by-step solution

Why the other options are wrong

• (1) This adds the magnitudes. An electron and a proton cancel each other's charge, so only the difference between the two numbers counts.
• (2) Squaring the numbers has no basis: charge is additive, so n particles of charge e carry ne, not n²e. It also adds where it should subtract.
• (3) Squared numbers again, and the sign is reversed: n₁ counts the electrons, which are negative, so their term must be subtracted.

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