A thin conducting ring of radius R is given a charge +Q. The electric field at the centre O of the ring due to the charge on the part AKB of the ring is E. The electric field at the centre due to the charge on the part ACDB of the ring is 
              

1.  3E along KO

2.  E along OK

3.  E along KO

4.  3 E along OK

A sphere encloses an electric dipole with charges $\pm 3\times {10}^{-6}C$. What is the total electric flux through the sphere?

(1) -3$\times {10}^{-6}$

(2) zero

(3) 3$\times {10}^{-6} N{m}^2/C$

(4) 6$\times {10}^{-6} N{m}^2/C$

An electric dipole is placed at an angle of 30 ° with an electric field intensity 2 x 10⁵ N/C. It experiences a torque equal to 4 Nm. The charge on the dipole, if the dipole length is 2 cm, is

1.  8mC

2.  2mC

3.  5mC

4.  

A square surface of side L m is in the plane of the paper. A uniform electric field  (V/m), also in the plane of the paper, is limited only to the lower half of the square surface, (see figure). The electric flux in SI units associated with the surface is : 

1. $E{L}^2/\left(2{\epsilon }_0\right)$

2. $E{L}^2/2$

3. zero

4. $E{L}^2$

A hollow cylinder has a charge q coulomb within it(at the geometrical centre). If ϕ is the electric flux in unit of voltmeter associated with the curved surface B, the flux linked with the plane surface A in unit of voltmeter will be: 

1. $\frac{1}{2}\left(\frac{q}{{\epsilon }_0}-\Phi \right)$

2. $\frac{q}{2{\epsilon }_0}$

3. $\frac{\Phi }{3}$

4. $\frac{q}{{\epsilon }_0}-\Phi$

A square surface of side L metre in the plane of the paper is placed in a uniform electric field E (volt/m) acting along the same place at an angle θ with the horizontal side of the square as shown in figure. The electric flux linked to the surface in unit of V-m, is 

1. $E{L}^2$

2. $E{L}^2 \cos \theta$

3. $E{L}^2 \sin \theta$

4. 0

An electron falls from rest through a vertical distance h in a uniform and vertically upward-directed electric field E. The direction of the electric field is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest in through the same vertical distance h. The time fall of the electron, in comparison to the time fall of the proton is :-

1. smaller

2. 5 times greater

3. 10 times greater

4. equal

A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field $\overrightarrow{\mathrm{E}}$. Due to the force q$\overrightarrow{\mathrm{E}}$, its velocity increases from 0 to 6 m/s in one-second duration. At that instant, the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively:-

1. 2 m/s, 4 m/s

2. 1 m/s, 3 m/s

3. 1 m/s, 3.5 m/s

4. 1.5 m/s, 3 m/s