Question

(a) A point charge Q = 100 mu C is placed at origin. Find electric field vector at point ( 6 m , 8 m). (b) A point charge Q = 169 mu C is placed at (1 m , 2m , 3m). Find the electric field vector at the point (4m , 6m , 15m).

Answer 1

Given info : (a) A point charge Q = 100μC is placed at origin.

(b) A point charge Q = 169μC is placed at (1, 2, 3) m

To find : (a) electric field vector at point (6, 8) m is..

(b) electric field vector at the point (4, 6, 15) is...

solution : using formula, E = kq/|r|³ r

here r = $r_p-r_q$

(a) r = (6, 8) - (0, 0) = 6i + 8j

|r| = √(6² + 8²) = 10 m

now E = kq/|r|³ r

= (9 × 10^9 × 100 × 10^-6)/10³ (6i + 8j)

= 900(6i + 8j)

= (5400i + 7200 j) N/C

(b) r = (4, 6, 15) - (1, 2, 3) = (3, 4, 12) = 3i + 4j + 12k

|r| = √(3² + 4² + 12²) = √(9 +16 + 144) = 13 m

now E = kq/|r|³ r

= (9 × 10^9 × 169 × 10^-6)/(13)³ (3i + 4j + 12k)

= 9/13 × 10³ (3i + 4j + 12k)

= 692.3 (3i + 4j + 12k) N/C

Answer 2

Explanation:

Given ,

W= 100 j ,

Q = 20 C

As. W = V Q

V = W / Q

= 100 J / 20 C

= 5 V