JEE Main 2022 · 28 Jun · Shift 2 · Physics Q40

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PhysicsSingle correct+4 / -1Question 40 of 90

Two point charges A and B of magnitude $+8\times10^{-6}$ C and $-8\times10^{-6}$ C respectively are placed at a distance d apart. The electric field at the middle point O between the charges is $6.4\times10^4$ NC $^{-1}$ . The distance 'd' between the point charges A and B is :

2.0 m

3.0 m

1.0 m

4.0 m

Answer and worked solution

Official answer: B

Field at the middle. Both charges give fields in the same direction: $E=2\cdot\dfrac{kq}{(d/2)^2}=\dfrac{8kq}{d^2}$ .

Solve. $d^2=\dfrac{8\times9\times10^9\times8\times10^{-6}}{6.4\times10^4}=9$ , so $d=3$ m.

(B)

Topics:Electric field

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JEE Main 2022 · 28 Jun · Shift 2, Physics question 40