Question

Two charges +10°C and +40°C are placed 12 cm apart in air. Find the position where electric intensity is zero from +10°C
charge​

Answer 1

Answer:

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Answer 2

Let that is situated at 'r' distance from 10C charge.

Eletric field intensity is 0, means both the charges create the equal amount of field intensity :

=> k(10)/r² = k(40)/(12cm - r)²

=> 10/r² = 40/(12 - r)²

=> (12 - r)² = 4r²

=> 144 + r² - 24r = 4r²

=> 144 - 3r² - 24r = 0

=> r² + 8r - 48 = 0

=> r² + 12r - 4r - 48 = 0

=> r(r + 12) - 4(r - 12) = 0

=> (r + 12)(r - 4) = 0

=> r = 4 (r ≠ -ve)

Hence electric intensity is 0 at x = 4cm = 0.04m from 10C.