Question

An aluminium nail has an excess charge of + X coulomb. If the charge of an electron is -e, the number of electrons that must be added to the nail to make it electrically neutral is
1. Xe
2. Xe²
3. X + e
4. X/e

Answer 1

Correct Answer - Option 4 : X/e

The correct answer is option 4) i.e. X/e

CONCEPT:

• Electric charge is a fundamental property of matter that causes the matter to experience a force when kept in electric and magnetic fields.
  • There are two types of charges possessed by matter - negative charge and positive charge.
  • The matter that is neither positive nor negative is said to be neutral.
  • The electric charge of the matter comes from the charge carried by electrons and protons at the atomic level.
  • The SI unit of electric charge is coulomb (C).

EXPLANATION:

Excess charge on aluminium nail = +X coulomb

• Thus, the given aluminium nail is positively charged. To make it electrically neutral, -X coulomb of charge must be added to it so as to make it neutral.

• A negative charge can be added to the nail by using electrons as they are negatively charged.

• Charge of an electron = -e coulomb

Number of electrons required for -X coulomb = \(\frac{-X }{-e} = \frac{X}{e}\)