Question

calculate the magnitude of electric field at a point distance
1 ) 5mm from +2nC
2 ) 0.4m from -12micro C​

Answer 1

we have to calculate the magnitude of electric field at a point distance

(1) 5mm from +2 nC

(2) 0.4 m from -12μC

Solution : we know, electric field at point located r distance from the charge q is given by |E| = kq/r²

(1) r = 5mm = 5 × 10¯³ m , q = 2nC = 2 × 10^-9 C

So, E = (9 × 10^9 × 2 × 10^-9)/(5 × 10¯³)²

= (18/25) × 10⁶ N/C

= 7.2 × 10⁵ N/C

(2) r = 0.4 m , q= 12μC = 12 × 10¯⁶ C [ only magnitude is taken because we have to find magnitude of electric field]

so E = (9 × 10^9 × 12 × 10^-6)/(0.4)²

= (108 × 10^-3)/(0.16) N/C

= 0.675 N/C