Potential Energy Is Defined for a System

Q. Two equal negative charges $-q$ each are fixed at points $(0,-a)$ and $(0,a)$ on y-axis. A positive charge $Q$ is released from rest at the point $(2a,0)$ on the $x$ - axis. The charge $Q$ will

1. execute simple harmonic motion about the origin
2. move to the origin and remain at rest
3. move to infinity
4. execute oscillatory but not simple harmonic motion

Q. If the P.E of a system decreases by 40 J while the K.E remains constant, then the work done by external agent will be.

1. 40 J
2. -40 J
3. 20 J
4. 0 J

Q. If the P.E of a system decreases by 40 J while the K.E remains constant, then the work done by external agent will be.

1. 40 J
2. -40 J
3. 20 J
4. 0 J

Q. Two identical thin rings each of radius R meters are coaxially placed at a distance R meters apart. If $Q_1$ coulomb and $Q_2$ coulomb are respectively the charges uniformly spread on the two rings, the work done in moving a charge q from the centre of one ring to that of other is

1. Zero
2. $\frac{q(Q_2-Q_1)(\sqrt{2}-1)}{\sqrt{2}.4\pi {ϵ}_{0}R}$
3. $\frac{q\sqrt{2}(Q_1+Q_2)}{4\pi {ϵ}_{0}R}$
4. $\frac{q(Q_1+Q_2)(\sqrt{2}+1)}{\sqrt{2}.4\pi {ϵ}_{0}R}$

Q. Two identical thin rings each of radius R meters are coaxially placed at a distance R meters apart. If $Q_1$ coulomb and $Q_2$ coulomb are respectively the charges uniformly spread on the two rings, the work done in moving a charge q from the centre of one ring to that of other is

1. Zero
2. $\frac{q(Q_2-Q_1)(\sqrt{2}-1)}{\sqrt{2}.4\pi {ϵ}_{0}R}$
3. $\frac{q\sqrt{2}(Q_1+Q_2)}{4\pi {ϵ}_{0}R}$
4. $\frac{q(Q_1+Q_2)(\sqrt{2}+1)}{\sqrt{2}.4\pi {ϵ}_{0}R}$