Electric charges

What is the value of minimum force acting between two charges placed at 1 m apart from each other

• $K\ e$

• $K\ e^2$

• $\frac{Ke}{4}$

• $\frac{Ke^2}{9}$

For a point charge, the graph between electric field versus distance is given by :

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Two protons are released from rest, with only the electrostatic force acting. Which of the following statements  is NOT true about them as they move apart? 

• Their electric potential energy keeps decreasing.

• Their electric potential energy keeps increasing.

• Their acceleration keeps decreasing.

• Their kinetic energy keeps increasing.

Answer explanation

As two protons move apart, they repel each other due to their positive charge, causing their electric potential energy to increase. Therefore, the statement "Their electric potential energy keeps increasing" is NOT true.

Two charges $3\times10^{-5}C$  and $5\times10^4C$  are placed at a distance 10 cm from each other. Find the value of electrostatic force acting between them.

•  $13.5\times10^{11}N$  

•  $40\times10^{11}N$  

•  $180\times10^9N$  

•  $13.5\times10^{10}N$  

An electric dipole is placed in a uniform field. The resultant force acting on it -------.

• always be zero

• depends on its relative position

• never be zero

• depends on its dipole moment

Answer explanation

In a uniform electric field, the forces on the positive and negative charges of the dipole are equal and opposite, resulting in a net force of zero. Therefore, the correct answer is that the resultant force acting on it always be zero.

What is the magnitude of the electric field intensity at a point where a proton experiences an electrostatic force of magnitude 2.30 x 10^-25 newton?

• 1.44 x 10^-6 N/C

• 3.68 x 10⁶ N/C

• 1.44 x 10⁴⁴ N/C

• 3.68 x 10^-44 N/C

Answer explanation

The electric field intensity (E) can be calculated using the formula F = qE, where F is the force and q is the charge of the proton (1.6 x 10^-19 C). Rearranging gives E = F/q. Substituting F = 2.30 x 10^-25 N, we find E = 1.44 x 10^-6 N/C.

A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the electric flux will _____________.

• increase

• decrease

• remain same

• first decrease then increase

 $If\ \oint E.dS=0,\$   inside a surface, that means :

• Discontinued field lines inside the surface

• Charge is present inside the surface

• there is no net charge present inside the surface

• Uniform electric field inside the surface

Statement (1): The electric field lines never cross each other.

      Statement (2): If electric field lines cross each other, the field at the point of  intersection will not have a unique direction, which is not possible.

• Electric field lines can cross each other.) Both statements are correct Statement (2) is the correct explanation for Statement (1)Both statements are correct Statement (2) is the correct explanation for Statement (1)

• Electric field lines can form loops.Both statements are correct Statement (2) is not the correct explanation for   

          Statement (1)

• TrueStatement (1) is correct but Statement (2) is wrong.

• The direction of the electric field is always random.Statement (2) is correct but Statement (1) is wrong.

   

Which of the following is deflected by electric field

• Neutrons            

• Photons
• Sound waves
• Charged particles (e.g., electrons, protons)