Physics Circle home Student Login

Home›Chapters›Electrostatics PYQs›Electric Field & Field Lines›Question 35

JEE Main 2020 (6 Sep, Shift 1) · Electric Field & Field Lines

Electric Field & Field Lines question from JEE Main 2020 (6 Sep, Shift 1)

Q35JEE Main 2020 · 6 SEP · SHIFT 1Medium

Electric Field & Field Lines

Charges Q1 and Q2 are at points A and B of a right angle triangle OAB (see figure). The resultant electric field at point O is perpendicular to the hypotenuse, then

Q1Q2\frac{Q_1}{Q_2} is proportional to:

Figure

Show answer and solution

Answer: (c)

  1. At OO: E1=kQ1x12E_1 = \dfrac{kQ_1}{x_1^2} along OAOA and E2=kQ2x22E_2 = \dfrac{kQ_2}{x_2^2} along OBOB (in magnitude).
  2. Hypotenuse ABAB has direction (x2,−x1)(x_2, -x_1), so a perpendicular has direction (x1,x2)(x_1, x_2), i.e. E2E1=x1x2\dfrac{E_2}{E_1} = \dfrac{x_1}{x_2}.
  3. Q2x12Q1x22=x1x2⇒Q1Q2=x1x2\dfrac{Q_2 x_1^2}{Q_1 x_2^2} = \dfrac{x_1}{x_2} \Rightarrow \dfrac{Q_1}{Q_2} = \dfrac{x_1}{x_2}
  4. So the answer is (c) x1x2\dfrac{x_1}{x_2}.
Report a mistake

More questions on Electric Field & Field Lines