CBSE Class 12 Physics Electric Charges And Fields Worksheet Set A

CBSE Class 12 Physics Electric Charges And Fields Important Questions (1).Students can download these worksheets and practice them. This will help them to get better marks in examinations. Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects. 

 1 What are the basic properties of electric charge?

2 Give the value of charge on an electron. 

3 If 109 electrons move out of a body to another body every second, how much time is required to get a total charge of 1C on the other body? 

4 How much positive and negative charge is there in a cup of water?

5 State Coulomb’s law. Give vector form of the equation for finding the force acting between any two charges.

Important Questions for NCERT Class 12 Physics Electric Charges And Fields

Question. Two point charges A and B, having charges +Q and –Q respectively, are placed at certain distance apart and force acting between them is F. If 25% charge of A is transferred to B, then force between the charges 
becomes
(a) 4F/3
(b) F
(c) 9F/16
(d) 16F/9

Question. The electrostatic potential inside a charged spherical ball is given by f = ar2 + b where r is the distance from the centre a, b are constants. Then the charge density inside the ball is   
(a) –6aε₀r
(b) –24paε₀
(c) –6aε₀
(d) –24paε₀r

Question. A hollow insulated conduction sphere is given a positive charge of 10 mC. What will be the electric field at the centre of the sphere if its radius is 2 m?   
(a) Zero
(b) 5 mCm^–2
(c) 20 mCm^–2
(d) 8 mCm^–2

Question. Suppose the charge of a proton and an electron differ slightly. One of them is –e, the other is (e + De). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then De is of the order of  
[Given: mass of hydrogen mh = 1.67 × 10^–27 kg]   
(a) 10^–23 C
(b) 10^–37 C
(c) 10^–47 C
(d) 10^–20 C 

Question. Which of the following pair of quantities do not have the same dimensions : 
(a) Potential gradient, electric field
(b) Torque, kinetic energy
(c) Light year, time period
(d) Impedance, reactance

Question. Two identical charged spheres suspended from a common point by two massless strings of lengths l, are initially at a distance d (d < < l) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity v.
Then v varies as a function of the distance x between the spheres, as   
(a) v ∝ x–1/2
(b) v ∝ x–1
(c) v ∝ x1/2
(d) v ∝ x

Question. The potential at a point P due to an electric dipole is 1.8 × 10⁵V. If P is at a distance of 50 cm apart from the centre O of the dipole and if CP makes an angle 60° with the positive side of the axial line of the dipole, what is the moment of the dipole?   
(a) 10 C–m
(b) 10^–3 C –m
(c) 10^–4 C–m
(d) 10^–5 C–m

Question. Two point charges +q and –q are held fixed at (–d, 0) and (d, 0) respectively of a x – y coordinate system. Then   
(a) the electric field E at all points on the axis has the same direction
(b) work has to be done in bringing a test charge from ¥ to the orgin
(c) electric field at all points on y-axis is along x-axis
(d) the dipole moment is 2qd along the x-axis

Question. When air is replaced by a dielectric medium of constant K, the maximum force of attraction between two charges separated by a distance   
(a) increases K times
(b) remains unchanged
(c) decreases K times
(d) increases K^–1 times.

Question. A charge q is placed at the centre of the line joining two equal charges Q. The system of the three charges will be in equilibrium if q is equal to   
(a) –Q/4
(b) Q/4
(c) –Q/2
(d) Q/2

Question. “Parsec” is the unit of : 
(a) time
(b) distance
(c) frequency
(d) angular acceleration

Question. Point charges +4q, –q and +4q are kept on the X-axis at point x = 0, x = a and x = 2a respectively. Then   
(a) only –q is in stable equilibrium
(b) all the charges are in stable equilibrium
(c) all of the charges are in unstable equilibrium
(d) none of the charges is in equilibrium.

Question. An electron falls from rest through a vertical distance h in a uniform and vertically upward directed electric field E. The direction of electric field is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest in it through the same vertical distance h. The time of fall of the electron, in comparison to the time of fall of the proton is 
(a) smaller
(b) 5 times greater
(c) 10 times greater
(d) equal 

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