**NEET Electrostatic Practice Test**

**Questions No:1**

The centres of two identical small conducting spheres are 1 m apart. They carry charges of opposite kind and attract each other with a force F. When they are connected by a conducting thin wire they repel each other with a force \( \frac{F}{3} \) . What is the ratio of magnitude of charges carried by the spheres initially?

[A] 1 : 1

[B] 2 : 1

[C] 3 : 1

[D] 4 : 1

**Questions No:2**

A metallic sphere having no net charge is placed near a finite metal plate carrying a positive charge. The electric force on the sphere will be

[A] towards the plate

[B] away from the plate

[C] parallel to the plate

[D] zero

**Questions No:3**

The insulation property of air breaks down at E = 3 x 10

^{6}v/m . The maximum charge that can be given to a sphere of diameter 5 m is approximately (in coulombs)

[A] 2X\( 10^{-2} \)

[B] 2X\(10{^-3} \)

[C] 2X\( 10^{-4}\)

[D] 2X\( 10^{-5} \)

**Questions No:4**

The distance between the two charges 25µ C and 36 µ C is 11 cm At what point on the line joining the two, the intensity will be zero?

[A] At a distance of 5 cm from 25µ C

[B] At a distance of 5 cm from 36µ C

[C] At a distance of 4 cm from 25 µ C

[D] At a distance of 4 cm from 36µ C

**Questions No:5**

The electric field near a conducting surface having a uniform surface charge density σ is given by

[A] \( \frac{σ}{ ε_0}\) and is parallel to the surface

[B] \( \frac{2σ}{ ε_0}\) and is parallel to the surface

[C] \( \frac{σ}{ ε_0}\) and is normal to the surface

[D] \( \frac{2σ}{ ε_0}\) and is normal to the surface

**Questions No:6**

The unit of electric field is not equivalent to

[A] N/C

[B] J/C

[C] V/m

[D] J/C-M

**Questions No:7**

The unit of intensity of electric field is

[A] Newton/coulomb

[B] Joule/coulomb

[C] Volt-metre

[D] Newton/metre

**Questions No:8**

Two spheres of radius a and b respectively are charged and joined by a wire. The ratio of electric field of the spheres is

[A] \( \frac{a}{b} \)

[B] \( \frac{b}{a} \)

[C] \( \frac {a^2}{b^2} \)

[D] \(\frac{b^2}{a}\)

**Questions No:9**

A cube of side b has a charge q at each of its vertices. The electric field due to this charge distribution at the centre of this cube will be \( \frac{1}{4πε _0} \) times

[A] \( \frac{q}{b^2} \)

[B] \( \frac{q}{2b^2} \)

[C] \( \frac{32q}{b^2} \)

[D] zero

**Questions No:10**

Electric field intensity at a point in between two parallel sheets with like charges of same surface charge densities (σ)

[A] \( \frac{σ}{ 2 ε_0} \)

[B] \( \frac{σ}{ε_0} \)

[C] Zero

[D] \( \frac{2σ}{ε_0} \)

**Questions No:11**

Two point charges (+Q) and (— 2Q) are fixed on the X-axis at positions aand 2 a from origin respectively. At what positions on the axis, the resultant electric field is zero?

[A] Only x = \( \sqrt{2}a \)

[B] Only x =\( \sqrt{2}a \)

[C] Both x = ± \( \sqrt{2}a \)

[D] Only x = \( \frac{3a}{2} \)

**Questions No:12**

Two point charges q and 2q are placed some distance apart. If the electric field at the location of q be E, then that at the location of 2 q will be

[A] 3E

[B] \( \frac{E}{2} \)

[C] E

[D] None of these

**Questions No:13**

Infinite charges of magnitude q each are lying at x = 1, 2, 4, 8, … metre on X-axis. The value of intensity of electric field at point X = 0 due to these charges will be

[A] 12 x\(10^9\) q N/C

[B] zero

[C] 6x\(10^9\) q N/C

[D] 4x\(10^9\) q N/C

**Questions No:14**

Angle between equipotential surface and lines of force is

[A] zero

[B] \(180^0\)

[C] \(90^0\)

[D] \( 45^0\)

**Questions No:15**

If a charged spherical conductor of radius 10 cm has potential V at a point distant 5 cm from its centre, then the potential at a point distant 1 5 cm from the centre will be

[A] \( \frac{1}{3} \) V

[B] \( \frac{2}{3} \) V

[C] \( \frac{3}{2} \) V

[D] 3 V

**Questions No:16**

Two unilike charges of magnitude q are separated by a distance 2d. The potential at a point midway between them is

[A] zero

[B] \( \frac{1}{4πε _0} \)

[C] \( \frac{1}{4πε_0} \) \( \frac{q}{d} \)

[D] \( \frac{1}{4πε_0} \)\( \frac{2q}{d} \)

**Questions No:17**

Two spheres A and B of radius a and b respectively are at same electric potential. The ratio of the surface charge densities of A and B is

[A] \( \frac{a}{b} \)

[B] \( \frac{b}{a} \)

[C] \( \frac{ a^2}{ b^2} \)

[D] \( \frac{ b^2}{ a^2} \)

**Questions No:18**

Point charge q

_{1}= 2 µ C and q

_{2}= – 1 µ C are kept at points x = 0 and x = 6 respectively. Electrical potential will be zero at points

[A] x = 2 and x = 9

[B] x = 1 and x = 5

[C] x = 4 and x = 1 2

[D] x = – 2 and x = 2

**Questions No:19**

Eight small drops, each of radius rand having same charge q are combined to form a big drop. The ratio between the potentials of the bigger drop and the smaller drop is

[A] 8 : 1

[B] 4 : 1

[C] 2 : 1

[D] 1 : 8

**Questions No:20**

Eight oil drops of same size are charged to a potential of 50 V each. These oil drops are merged into one single large drop. What will be the potential of the large drop?

[A] 50V

[B] 100V

[C] 200V

[D] 400V

**Questions No:21**

Electric potential at a point X from the centre inside a conducting sphere of radius R and carrying charge Q is

[A] \( \frac{1}{4πε _0} \) \( \frac{Q}{R} \)

[B] \( \frac{1}{4πε _0} \) \( \frac{Q}{X} \)

[C] \( \frac{1}{4πε_0}\) \( \frac{X}{Q} \)

[D] Zero