CBSE Class 12 Physics Electric Charges And Fields Worksheet Set B

CBSE Class 12 Physics Electric Charges And Fields Important Questions (2).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.Define Torque. Find the torque acting on an electric dipole placed in a uniform electric field. Give the conditions for torque acting on an electric dipole is

(a) zero and (b) maximum 

2 How can you explain a comb run through dry hair attracts pieces of paper?

3 Define linear charge density. Give its SI unit of measurement. Also give the formula to find the linear charge density. 

4 Define the following. Also give their SI units of measurement?

(a) Surface charge density (b) volume charge density. 

5 State & prove Gauss’s Law. 

6 Give any four important points regarding Gauss’s law. 

Important Questions for NCERT Class 12 Physics Electric Charges And Fields

Question. A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field vector E. Due to the force qEvector , its velocity increases from 0 to 6 m s–1 in one second duration. At that instant the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively 
(a) 2 m s^–1, 4 m s^–1
(b) 1 m s^–1, 3 m s^–1
(c) 1 m s^–1, 3.5 m s^–1
(d) 1.5 m s^–1, 3 m s^–1

Question. A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is   
(a) qEy
(b) qE²y
(c) qEy²
(d) q²Ey

Question. Which of the following pairs does not have similar dimensions ?
(a) tension and surface tension
(b) stress and pressure
(c) Planck’s constant and angular momentum
(d) angle and strain

Question. A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will   
(a) increase four times
(b) be reduced to half
(c) remain the same
(d) be doubled

Question. A charge Q is situated at the corner of a cube, the electric flux passed through all the six faces of the cube is   
(a) Q/6ε₀
(b) Q/8ε₀
(c) Q/ε₀
(d) Q/2ε₀

Question. A point charge + q is placed at the centre of a cube of side l. The electric flux emerging from the cube is   
(a) 6ql2/ε0
(b) q/6l2ε0
(c) zero
(d) q/ε0

Question. Three point charges +q, –2q and +q are placed at points (x = 0, y = a, z = 0), (x = 0, y = 0, z = 0) and (x = a, y = 0, z = 0) respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are   
(a) 2qa along the line joining points (x = 0, y = 0, z = 0) and (x = a, y = a, z = 0)
(b) qa along the line joining points (x = 0, y = 0,z = 0) and (x = a, y = a, z = 0)
(c) 2qa along + x direction
(d) 2qa along + y direction. 

Question. A point Q lies on the perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole), then the electric field at Q is proportional to   
(a) p² and r^–3 
(b) p and r^–2
(c) p^–1 and r^–2
(d) p and r^–3

Question. An electric dipole is placed at an angle of 30° with an electric field intensity 2 × 10⁵ N C^–1.   
It experiences a torque equal to 4 N m. The charge on the dipole, if the dipole length is 2 cm, is
(a) 8 mC
(b) 2 mC
(c) 5 mC
(d) 7 mC

Question. Which of the following physical quantities do not have same dimensions? 
(a) pressure and stress
(b) tension and surface tension
(c) strain and angle
(d) energy and work.

Question. What is the flux through a cube of side a if a point charge of q is at one of its corner? 
(a) 2q/ε0
(b) q/8ε0
(c) q/ε0
(d) q/2ε0 . 6a²

Question. A hollow metal sphere of radius R is uniformly charged. The electric field due to the sphere at a distance r from the centre   
(a) decreases as r increases for r < R and for r > R
(b) increases as r increases for r < R and for r > R
(c) zero as r increases for r < R, decreases as rincreases for r > R
(d) zero as r increases for r < R, increases as r increases for r > R

Question. The electric field at a distance 3R/2 R from the centre of a charged conducting spherical shell of radius R is E.   The electric field at a distance R/2from the centre of the sphere is
(a) zero
(b) E
(c) E/2
(d) E/3

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 metres ?   
(a) 20 mC m^–2
(b) 5 mC m^–2
(c) zero
(d) 8 mC m^–2

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