Electric Potential at a Point in Space Due to a Point Charge Q

Q.

Six identical particles each of mass m are arranged at the corners of a regular hexagon of side length "L”. If the mass of one of the particles is doubled, the shift in the centre of mass?

1. 

2. 6L/7

3. L/7

4. L

Q. Charges of $+\frac{10}{3}\times {10}^{-9}C$ are placed at each of the four corners of a square of side 8 cm. The potential at the intersection of the diagonals is

1. $150\sqrt{2}$ volt
2. $1500\sqrt{2}$ volt
3. $900\sqrt{2}$ volt
4. 900 volt

Q. Two electric charges $12\mu C$ and $-6\mu C$ are placed 20 cm apart in air. There will be a point P on the line joining these charges and outside the region between them, at which the electric potential is zero. The distance of P from $-6\mu C$ charge is

1. 0.10 m
2. 0.15 m
3. 0.20 m
4. 0.25 m

Q. Two point charges $4\mu C$ and $9\mu C$are separated by a distance of 50 cm. The potential at the point between them where the field has zero strength is

1. $4.5\times {10}^{5}V$
2. $9\times {10}^{5}V$
3. $9\times {10}^{4}V$
4. Zero

Q. 20.Which is the strongest force coulombs force and gravitational force

Q. Two point charges 20mC and - 60 mC are separated by a distance of 16cm. The net electric potential is zero on the line joining them

1. At a distance of 4cm from 20mC in between the charges
2. At a distance of 8cm from 20mC and 24cm from -60 mC
3. Both of the above
4. None of the above

Q. Two metal spheres one of radius $R$ and $2R$ respectively. have the same surface charge density $\sigma .$ They are brought in contact and separated. What will be the new surface charge densities on them?

Q. An infinite number of charges of equal magnitude q, but of opposite sign are placed alternately starting with positive charge along x- axis at x = 1 m; x = 2 m, x = 4 m, x= 8 m and so on. The electric potential at the point x = 0 due to these charges will be (in S.I units and k = $\frac{1}{4\pi {ϵ}_0}$

1. $\frac{kq}{2}$
2. $\frac{kq}{3}$
3. $\frac{k2q}{3}$
4. $\frac{k3q}{2}$

Q. Charges are placed on the vertices of a square as shown. Let $\overrightarrow{E}$ be the electric field and V the potential at the centre. If the charges on A and B are interchanged with those on D and C respectively, then [AIEEE-2007]

1. Both $\overrightarrow{E}$ and V change
2. $\overrightarrow{E}$ and V remain unchanged
3. $\overrightarrow{E}$ changes, V remains unchanged
4. $\overrightarrow{E}$ remains unchanged, V changes

Q. A charge +q is fixed at each of the points $x=x_0,x=3x_0,x=5x_0\dots \dots$ infinity, on the x - axis and a charge -q is fixed at each of the points $x=2x_0,x=4x_0,x=6x_0\dots \dots$ infinity. Here $x_0$ is a positive constant. The potential at the origin due to the above system of charges is

1. \N
2. $\frac{q}{8\pi {ϵ}_0{x}_{0}ln2}$
3. $\infty$
4. $\frac{qln2}{4\pi {ϵ}_0{x}_0}$

Q. A proton, a deuteron and an $\alpha$-particle is accelerated through the same potential difference from rest, enters a region of uniform magnetic field, moving at right angles to it. What is the ratio of their kinetic energies?

Q. Four electric charges $+q,+q,-q$ and $-q$ are placed at the corners of a square of side $2L$ (see figure). The electric potential at point $A$ (midway between the two charges $+q$ and $-q$ ) is

1. $\frac{1}{4\pi {\in }_0}\frac{2q}{L}(1+\sqrt{5})$
2. $\frac{1}{4\pi {\in }_0}\frac{2q}{L}(1+\frac{1}{\sqrt{5}})$
3. $\frac{1}{4\pi {\in }_0}\frac{2q}{L}(1-\frac{1}{\sqrt{5}})$
4. Zero

Q. Charges $+q$ and $-q$ are placed at the vertices $\text{B}$ and $\text{C}$ of an isosceles triangle. The potential at the vertex $\text{A}$ is

1. $\frac{1}{4\pi {ϵ}_0}.\frac{q}{\sqrt{a^2+b^2}}$
2. $\frac{1}{4\pi {ϵ}_0}.\frac{-q}{\sqrt{a^2+b^2}}$
3. zero
4. $\frac{1}{4\pi {ϵ}_0}.\frac{2q}{\sqrt{a^2+b^2}}$