Electric Charges and Fields

The number of electron in 2 coulomb of charge is

• 5 × 10²⁹

• 12.5 × 10¹⁸

• 1.6 × 10¹⁹

• 9 × 10¹¹

Which of the following materials is the best conductor of electricity ?

• Platinum

• Gold

• Silicon

• Copper

A point charge +q is placed at the centre of a cube of side L. The electric flux emerging from the cube is

• $\frac{\mathrm{q}}{{\mathrm{\epsilon }}_0}$

• zero

• $\frac{6{\mathrm{qL}}^2}{{\mathrm{\epsilon }}_0}$

• $\frac{\mathrm{q}}{6{\mathrm{L}}^2{\mathrm{\epsilon }}_0}$