CBSE Board Exam 2020: Important MCQs (with Answers) for Class 12 Physics - Chapter 1 Electric Charges and Fields; Also Important for JEE Main 2020
Check important solved MCQs (Multiple Choice Questions) for CBSE Class 12 Physics Board Exam 2020 (Also useful for JEE Main 2020). CBSE Date Sheet 2020 has been released & as per CBSE Board Exam 2020 for Class 12 Physics is scheduled to be held on 2nd March. as per new CBSE exam pattern, Multiple Choice Questions will be asked in Class 12 Physics Board Exam 2020. These multiple choice questions are also helpful for the preparation of other competitive exams like UPSEE 2020, WBJEE etc.
MCQs (Multiple Choice Questions) for Class 12 Physics with Answers - Chapter 1 Electric Charges and Fields
1. The Gaussian surface for calculating the electric field due to a charge distribution is:
a) Any closed surface around the charge distribution
b) Any surface near the charge distribution
c) A spherical surface
d) A symmetrical closed surface at every point of which electric field has a single fixed value.
For calculating electric field, a symmetrical closed surface at every point of which electric field has a single fixed value.
2. How many electrons are there in ‒1 coulomb?
a) 6.25 × 1018
b) 62.5 × 1018
c) 6.023 × 1023
d) 1.6 × 10-19
As, q = n e.
Given, q = 1 C, e = 1.6 × 10‒19 C and n =?
Therefore, n = 0.625 × 1019 = 6.25 × 1018.
3. The S.I. unit for surface integral of electric field is:
The SI unit of electric field is NC-1 or V/m.
4. The value of charge q at the centre of two equal and like charges Q so that the three are in equilibrium is:
Let the charges be placed at points A and B separated by a distance 2 x as shown in figure.
If a charge q is placed at the centre then, the system will be in equilibrium if net force on each charge is zero.
We will find net force on charge Q at point B and equate it to zero
5. When an electric dipole is placed in a uniform electric field, it experiences
a) Force as well as torque
b) Torque but no net force
c) Force but no torque
d) Neither any force nor any torque
When an electric dipole is placed in a uniform electric field then, net force on the dipole is zero and net torque is not zero.
7. VAand VBare two points on a curved equipotential surface then,
a) VA> VB
b) VA< VB
c) VA= VB
d) Relation between the two can’t be predicted
All points in an equipotential surface have same potential. Therefore, VA = VB.
10. Electric filed is zero in case of a charged conducting shell at any:
a) Interior point
b) Outer point
c) Beyond 2 meters
d) Beyond 10 meters
Electric field inside a charged conductor is always zero.