IIT-JEE 2010 · Paper 1 · Physics Q65

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PhysicsMultiple correct+3Question 65 of 84

A few electric field lines for a system of two charges $Q_1$ and $Q_2$ fixed at two different points on the x-axis are shown in the figure. These lines suggest that

Field lines between two point charges Q₁ (left) and Q₂ (right) on the x-axis: many lines leave Q₁ and curve round to Q₂, and more lines emerge from Q₁ in total than end on Q₂.

|Q_1|>|Q_2|

|Q_1|<|Q_2|

at a finite distance to the left of

Q_1

the electric field is zero

at a finite distance to the right of

Q_2

the electric field is zero

Answer and worked solution

Official answer: A, D

From the field lines. More lines leave $Q_1$ than end on $Q_2$ , so $|Q_1|>|Q_2|$ , and the lines run from one to the other, so the charges have opposite signs.

Null point. For unlike charges the field vanishes outside the pair, on the side of the smaller charge: at a finite distance to the right of $Q_2$ .

(A) True. (B) False. (C) False. (D) True.

(A), (D)

Topics:Electric field

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IIT-JEE 2010 · Paper 1, Physics question 65