A point charge q is placed at the center of the open face of a hemispherical surface as shown in the figure. The flux linked with the surface is:

       

1.  zero

2.  $\frac{q}{2{\epsilon }_0}$

3.  $\frac{q}{{\epsilon }_0}$

4.  $q\pi r^2$

Order of q/m ratio of the proton, $\alpha$-particle and electron is

1.  e > p > $\alpha$

2.  p > $\alpha$ > e

3.  e > $\alpha$ > p

4.  p > e > $\alpha$

A body can be negatively charged by

1.  Giving excess of electrons to it

2.  Removing some electrons from it

3.  Giving some protons to it

4.  Removing some neutrons from it

An electric field in space is given by $\left(10\hat{i} + 3\hat{j} + 4\hat{k}\right)$ unit, then electric flux through a surface of area 1 unit lying in yz plane is

1.  10 units

2.  17 units

3.  30 units

4.  40 units

When a positive charge inside a metallic shell of thickness t is moved, then induced surface charge density

1 On inner surface will same and on the outer surface will change

2 On inner surface will change and on the outer surface will same

3 On the inner and outer surface will the same

4 On the inner and outer surface will change

Charge distribution at three vertices of an equilateral of side is shown in the figure. The net electric dipole moment of the system is

1.  $2\sqrt{3}qa\hat{j}$

2.  $-2\sqrt{3}qa\hat{j}$

3.  $2\sqrt{3}qa\hat{j}+2\sqrt{3}qa\hat{j}$

4.  $-2\sqrt{3}qa\hat{j}-2\sqrt{3}qa\hat{j}$

A circular plate subtends a solid angle $\mathrm{\pi }$ steradian at a point where a point charge 2Q is kept. The total electric flux through the circular plate is

1$\frac{Q}{4{\epsilon }_0}$

2 $\frac{Q}{2{\epsilon }_0}$

3 $\frac{2Q}{3{\epsilon }_0}$

4 $\frac{2Q}{{\epsilon }_0}$

A uniform electric field of strength E exists in a region. An electron is projected in the region perpendicularly with speed v as shown in the diagram. electron exits at point B. The electric field in the region is given by 

1 $\overrightarrow{E}=\frac{2xm{v}^2}{e{y}^2}\hat{i}$

2 $\overrightarrow{E}=\frac{xm{v}^2}{e{y}^2}\hat{i}$

3 $\overrightarrow{E}=-\frac{xm{v}^2}{e{y}^2}\hat{i}$

4 $\overrightarrow{E}=-\frac{2xm{v}^2}{e{y}^2}\hat{i}$

A point charge is placed at the center of the spherical Gaussian surface. The electric flux through the surface is changed if the:

In a region, volume charge density varies with radial distance r as $p=\frac{K}{r}$ where K is positive constant. The electric field E Varies with the radial distance in the region as

1. $\mathrm{E}\propto \mathrm{r}$

2. $\mathrm{E}\propto \frac{1}{r^2}$

3. $\mathrm{E}\propto r^2$

4. $\mathrm{E}\propto {\mathrm{r}}^0$