Question

Intensity of electric field is a vector quantity.

1. Define intensity of electric field at a point.

2. Two small spheres A and B carrying charges 2µC and 6µC respectively are separated by a fixed distance. Intensity of electric field at the location of B due to A is E. Intensity of electric field at the location of A due B is

• E
• 3E
• 6E
• 12E

3. Two point charges +4nC and +5nC are placed at x = 0.2m and x = 0.3m respectively along the x axis. Find the magnitude and direction of intensity of electric field at the origin.

Answer 1

1. Intensity of electric field at point is the electrostatic force experienced by unit positive charge placed at that point.

2. 3E 

Intensity of electric field at the origin due to the negative charge

E_(-) = \(\frac{1}{4 \pi \varepsilon_0}\) \(\times \frac{5\times10^{-9}}{0.3^2}\)

E_(-) = 500NC^-1 along -ve x axis

Intensity of electric field at the origin due to the positive charge

E₍₊₎ = \(\frac{1}{4\pi\varepsilon_0}\times \frac{4\times10^{-9}}{0.2^2}\)

E₍₊₎ = 900NC^-1 along -ve x axis

Net intensity of electric field at the origin

E = E₍₊₎ + E_(-) = 500 + 900 = 1400 NC^-1 along -ve x axis.