Question

Two point charges Q1 and Q2 are placed at a distance R apart represent graphically the variation of force f on Q2 with(i) magnitude of Q2
(ii) distance from Q1
(iii) distance with 1/r^2

Answer 1

Given:

Two charges Q1, Q2.

Distance between Q1 and Q2 = R .

Magnitude of force on Q2 = F

Given:

Represent graphically the variation of force f on Q2 with

(i) magnitude of Q2

(ii) distance from Q1

(iii) distance with 1/r^2

Solution:

We know that the Coloumbic force of attraction between two charges Q1 and Q2, separated by a distance R is given by,

• F = Q1Q2/4π∈R²

Let 1/4π∈ = K, a constant  = 9  x $10^{9}$ Nm²/C²

Consider F.

• F = KQ1Q2/R²

We need to find variation of F with :

1. magnitude of Q2

• F = (kQ1/R²) x Q2
• Lets assume Q1, R are constant.
• F α Q2 , directly proportional.
• Hence F vs Q2 varitaion will be a straight line passing through origin.
• Slope = KQ1/R²

    2.distance from Q1 , R

• F = (kQ1Q2) / R²
• Lets assume Q1, Q2 are constant
• F α 1/R²
• F is inversely proportional to square of distance.
• It will be a hyperbola.

    3. with 1/R²

• F α 1/R²
• F is directly proportional to 1/R²
• F vs 1/R² will be a straight line through origin
• Slope = KQ1Q2

Hence we have represented graphically the variation of force f on Q2 with

(i) magnitude of Q2

(ii) distance from Q1

(iii) distance with 1/r^2