In this article, we are providing assertion reason questions for cbse class 12 physics chapter 1 electric charges and fields. Assertion Reason questions are a type of test question in which a statement or assertion is given, and the test-taker is asked to provide a reason or explanation for that statement. The aim is to test the test-taker’s understanding and application of a concept or idea.
Assertion Reason Questions for CBSE Class 12 Physics Chapter 1 Electric Charges and Fields
Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
(a) Both Assertion and Reason are correct, and the Reason is a correct explanation of the Assertion.
(b) Both Assertion and Reason are correct, but Reason is not a correct explanation of the Assertion.
(c) Assertion is correct, Reason is incorrect
(d) Both Assertion and Reason are correct.
Q.1. Assertion : The tyres of aircraft are slightly conducting.
Reason : If a conductor is connected to ground, the extra charge induced on conductor will flow to ground.
Answer
(b) Both the statements are independently correct.Q.2. Assertion : Coulomb force and gravitational force follow the same inverse-square law.
Reason : Both laws are same in all aspects.
Answer
(c) Coulomb force and gravitational force follow the same inverse-square law. But gravitational force has only one sign which is always attractive, while coulomb force can be of both signs which are attractive and repulsive.Q.3. Assertion : The coulomb force is the dominating force in the universe.
Reason : The coulomb force is weaker than the gravitational force.
Answer
(d) Gravitational force is the dominating force in nature and not coulomb’s force. Gravitational force is the weakest force. Also, Coulomb’s force > > gravitational force.Q.4. Assertion : Some charge is put at the centre of a conducting sphere. It will move to the surface of the sphere.
Reason : Conducting sphere has no free electrons at the centre.
Answer
(a) Because of repulsion, the free electrons will mole to the outer surface.Q.5. Assertion : If there exists coulomb attraction between two bodies, both of them may not be charged.
Reason : In coulomb attraction two bodies are oppositely charged.
Answer
(b) Coulomb attraction exists even when one body is charged, and the other is uncharged.Q.6. Assertion: Electron move away from a region of lower potential to a region of higher potential.
Reason: An electron has a negative charge.
Answer
aQ.7. Assertion : A metallic shield in form of a hollow shell may be built to block an electric field.
Reason : In a hollow spherical shield, the electric field inside it is zero at every point.
Answer
aQ.8. Assertion : Consider two identical charges placed distance 2d apart, along x-axis.
The equilibrium of a positive test charge placed at the point O midway between them is stable for displacements along the x-axis.
Reason: Force on test charge is zero.
Answer
(b) If +ve charge is displaced along x-axis, then net force will always act in a direction opposite to that of displacement and the test charge will always come back to its original position.Q.9. Assertion : When a conductor is placed in an external electrostatic field, the net electric field inside the conductor becomes zero after a small instant of time.
Reason : It is not possible to set up an electric field inside a conductor.
Answer
(c) Statement-1 is correct. The induced field cancels the external field. Statement-2 is false. When a current is set up in a conductor, there exists an electric field inside it.Q.10. Assertion : A uniformly charged disc has a pin hole at its centre. The electric field at the centre of the disc is zero.
Reason : Disc can be supposed to be made up of many rings. Also electric field at the centre of uniformly charged ring is zero.
Answer
(a) The electric field due to disc is superposition of electric field due to its constituent ring as given in Reason.Q.11. Assertion : Electric lines of force never cross each other.
Reason : Electric field at a point superimpose to give one resultant electric field.
Answer
bQ.12. Assertion : The Coulomb force is the dominating force in the universe.
Reason : The Coulomb force is weaker than the gravitational force.
Answer
dQ.13. Assertion : In a cavity within a conductor, the electric field is zero.
Reason : Charges in a conductor reside only at its surface.
Answer
aQ.14. Assertion : A point charge is brought in an electric field, the field at a nearby point will increase or decrease, depending on the nature of charge.
Reason : The electric field is independent of the nature of charge.
Answer
(c) The electric field will increase if positive charge is brought in an electric field.Q.15. Assertion : When bodies are charged through friction, there is a transfer of electric charge from one body to another, but no creation or destruction of charge.
Reason : This follows from conservation of electric charges.
Answer
(a) Conservation of electric charge states that the total charge of an isolated system remains unchanged with timeQ.16. Assertion : A metallic shield in form of a hollow shell may be built to block an electric field.
Reason : In a hollow spherical shield, the electric field inside it is zero at every point.
Answer
(a) The electrostatic shielding is possible by metallic conductor.Q.17. Assertion : Electric lines of field cross each other.
Reason : Electric field at a point superimpose to give one resultant electric field.
Answer
Assertion is Incorrect, Reason is correct. (d) Two field lines never intersect.Q.18. Assertion : A deuteron and an alpha-particle are placed in an electric field. If F1 and F2 be the forces acting on them and a1 and a2 be their accelerations respectively then, a1 = a2.
Reason : Forces will be same in electric field.
Answer
cQ.19. Assertion : On bringing a positively charged rod near the uncharged conductor, the conductor gets attracted towards the rod.
Reason : The electric field lines of the charged rod are perpendicular to the surface of conductor.
Answer
(b) Though the net charge on the conductor is still zero but due to induction negatively charged region is nearer to the rod as compared to the positively charged region. That is why the conductor gets attracted towards the rodQ.20. Assertion : The property that the force with which two charges attract or repel each other are not affected by the presence of a third charge.
Reason : Force on any charge due to a number of other charge is the vector sum of all the forces on that charge due to other charges, taken one at a time.
Answer
(b) Force on any charge due to a number of other charges is the vector sum of all the forces on that charge due to the other charges, taken one at a time. The individual force are unaffected due to the presence of other charges. This is the principle of superposition of charges.Assertion Reason Questions for CBSE Class 12 Physics
Assertion Reason questions are a type of assessment in which a statement or assertion is made and the student is then asked to provide a reason or explanation for that assertion. In the context of physics, these types of questions can be used to assess a student’s understanding of a particular concept, as well as their ability to apply that concept to a given situation.
One common format for an assertion reason question in physics might be as follows:
Assertion: The acceleration of an object is directly proportional to the net force acting on it.
Reason: This is because according to Newton’s second law, F = ma, where F is the net force on an object, m is its mass, and a is its acceleration.
In order to correctly answer this type of question, the student must not only understand the concept of acceleration and net force, but also be able to apply Newton’s second law to explain why the assertion is true.
Overall, assertion reason questions can be a useful tool for assessing a student’s understanding and application of physics concepts.