Test: Electric Charges and Fields - 1 - CUET Humanities MCQ

Since the hypotenuse of the triangle is √2 a, the net electrostatic energy is:

For U = 0, we require

Or, 
Hence, option 2 is the correct answer.

The body acquired a negative charge either by gaining electron or losing proton, losing proton is not easy for any body because it is only possible in nuclear reaction, So Acquired excess of electron is the correct option.

Key Idea: Like charges repel each other while unlike charges attract each other.
From Coulomb's law, the force of attraction/repulsion between two point charges q1 and q2 placed a distance r apart is given by
F =  N
When similar charges are taken
q₁ = 3 × 10^-6 C, q₂ = 8 × 10^-6 C
F =  ...(i)
(repulsive)
When additonal charge - 6 × 10⁶ C is given to each charge, then
F' = 
(attractive)
∴ F' =  N ... (ii)
Dividing Eq. (ii) by Eq. (i), we get

⇒ F' = - F/4
= -  = - 1.5 × 10^-3 N
Negative sign indicates, force is attractive.

The process of acquiring temporary electrification under the influence of a charged body is called induction.

At equilibrium,
T cos θ = mg --- (1)
T sinθ = qE --- ( 2)
Dividing (2) by (1), we get:

The angle between electric dipole moment and electric field intensity due to an electric dipole at a point on its equatorial line is 180° as both of them are in opposite directions.

The correct option is (3). In a non-uniform electric field, a dipole experiences a force, which gives it a translational motion, and a torque, which gives it a rotational motion.

Here, F_CA = F_CB = F_C
Hence, the resultant force on the charge at C is

The electric field is always perpendicular to the surface of a conductor. On the surface of a metallic solid sphere, the electric field is perpendicular to the surface and directed towards the centre of the sphere. Hence, the correct option is (4).

The electric field at a point P due to an infinite long plane sheet carrying a uniform charge density σ is given by .
It is independent of the distance of point P from the sheet and is therefore, uniform.
The direction of the electric field is away from the sheet and perpendicular to it, if σ is positive and is towards the sheet and perpendicular to it, if σ is negative.
Hence, 

and, 
From the superposition principle, the net electric field at point is E = E₁ + E₂ + E₃ 

=  which is option (3).