Two point charges q_A = 3 µC and q_B= –3 µC are located 20 cm apart in a vacuum. The electric field at the midpoint O of the line AB joining the two charges is:

1. 4.5×10⁶ N/C along OA
2. 5.4×10⁶ N/C along OA
3. 4.5×10⁶ N/C along OB
4. 5.4×10⁶ N/C along OB

Which of the following statements about electric field lines (due to static charges) is incorrect?

The figure below shows tracks of three charged particles in a uniform electrostatic field. Which particle has the highest charge to the mass ratio?

1. 2
2. 3
3. 1
4. 1 and 3

A conducting sphere of radius \(10\) cm has an unknown charge. If the electric field, \(20\) cm from the centre of the sphere is \(1.5\times10^3\) N/C and points radially inward, what is the net charge on the sphere?
1. \(-5.70\) nC
2. \(-6.67\) nC
3. \(6.67\) nC
4. \(5.70\) nC

Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude 17.0 x 10^-22 C/m². The electric field between the plates is: 

1. 0.96 × 10^-10   N/C
2. 1.92 × 10^{- 10}   N/C
3. 0
4. 3.84 × 10^-10   N/C

An oil drop of 12 excess electrons is held stationary under a constant electric field of $2.55\times {10}^{-4} N C^{-1}$. The density of the oil is $1.26 g c{m}^{-3}$. The radius of the drop is:

1. \(9.82\times10^{-4}\) mm
2. \(9.82\times10^{-7}\) mm
3. \(8.92\times10^{-4}\) mm
4. \(8.92\times10^{-7}\) mm

 

Which among the curves shown in the figure represents electrostatic field lines?
 

1.		2.
3.		4.

A particle of mass m and charge (–q) enters the region between the two charged plates initially moving along the x-axis with speed $v_x$ (as shown in the figure). The length of the plate is L and a uniform electric field E is maintained between the plates. The vertical deflection of the particle at the far edge of the plate is:

             
1. \(\frac{2 q E L^2}{3 m\left(v_x\right)^2}\)
2. \(\frac{2 q E L^2}{m\left(v_x\right)^2}\)
3. \(\frac{3 q E L^2}{2 m\left(v_x\right)^2}\)
4. \(\frac{q E L^2}{2 m\left(v_x\right)^2}\)

A spherical conductor of radius \(12~\text{cm}\) has a charge of \(1.6\times10^{-7}~\text{C}\) distributed uniformly on its surface. The electric field just outside the sphere is:
1. \(\text{zero}\)
2. \(10^5~ \text{NC}^{-1} \)
3. \(10^{-5}~ \text{NC}^{-1} \) 
4. \(10^{6 }~ \text{NC}^{-1} \)