Electrostatics & Capacitors · JEE Main previous year questions

2009 3 questions

1. Q452009 · 27 Apr 2009 · Shift 1

   A charge $Q$ is placed at each of the opposite corners of a square. A charge $q$ is placed at each of the other two corners. If the net electrical force on $Q$ is zero, then $Q/q$ equals:

   1. A.$-1$
   2. B.$1$
   3. C.$-\frac{1}{\sqrt{2}}$
   4. D.$-2\sqrt{2}$
   Show answer

   Answer: D

2. Q462009 · 27 Apr 2009 · Shift 1

   (This question contains Statement-1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements.) Statement-1 : For a charged particle moving from point $P$ to point $Q$, the net work done by an electrostatic field on the particle is independent of the path connecting point $P$ to point $Q$. Statement-2 : The net work done by a conservative force on an object moving along a closed loop is zero.

   1. A.Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-1.
   2. B.Statement-1 is true, Statement-2 is true; Statement-2 is not the correct explanation of Statement-1.
   3. C.Statement- 1 is false, Statement- 2 is true.
   4. D.Statement- 1 true, Statement- 2 is false
   Show answer

   Answer: A

3. Q472009 · 27 Apr 2009 · Shift 1

   Let $P(r)=\frac{Q}{\pi R^4}r$ be the charge density distribution for a solid sphere of radius $R$ and total charge $Q$. For a point '$p$' inside the sphere at distance $r_1$ from the center of the sphere, the magnitude of electric field is :

   1. A.$\frac{Q}{4\pi {ϵ}_0{r}_1^2}$
   2. B.$\frac{Q{r}_1^2}{4\pi {ϵ}_0{R}^4}$
   3. C.$\frac{Q{r}_1^2}{3\pi {ϵ}_0{R}^4}$
   4. D.0
   Show answer

   Answer: B