Solved paper for CBSE Class 11 Physics subject is available here. This paper contains important question from complete Class 11 Physics Syllabus. The format of this question paper is similar to the latest CBSE sample paper. All the questions of this sample paper are important for CBSE Class 11 Physics final exam 2018.
The format of CBSE Class 11 Physics Question Paper:
(a) All questions are compulsory.
(b) There are 26 questions in total. Questions 1 to 5 carry one mark each; questions 6 to 10 carry two marks each, questions 11 to 22 carry three marks each, question 23 carry four marks and questions 24 to 26 carry 5 marks each.
(c) There is no overall choice. However, internal choices have been provided in some questions.
(d) Use of calculator is not permitted.
(e) You may use the following physical constants wherever necessary.
Some randomly selected questions from CBSE Class 11 Solved Physics paper 2018:
Question : Find the number of significant figures in 0.007
Question : Is radius of gyration of a body is constant quantity?
No, because it depends of axis of rotation and also on distribution of mass of the body about this axis.
Question: In case of simple pendulum, which force keeps it in simple harmonic mmotion?
Component of weight (mg sinϕ) keeps the simple pendulum in simple harmonic motion.
Question: Which of the following is not a unit of energy?
Joule, Calories, Kilowatt
Kilowatt is not a unit of energy.
Question : How are pitch and least count of a spherometer are related?
Least count = (pitch)/(total number of division on the circular scale)
Question: Anil sitting on a swing, suddenly another boy, Hari jumps in and sits by his side. What will be effect on the periodic time of the swing?
There will be no effect on time period because time period does not depend on mass.
Question: Can two vectors of different magnitudes combined to give zero resultant? Will it be possible with the help of three vectors
No, two vectors of different magnitudes can’t have zero resultant. Yes.
Question: What is the work done in blowing a soap bubble of radius r and surface tension S?
Work done = surface tension × area of soap bubble = S × (4πr2) × 2 = 8SL.
Question: Which of the two conditions is not sufficient for simple harmonic motion, explain?
(a) acceleration ∝ displacement
(b) restoring force ∝ displacement
Here, the condition (a) is not sufficient, as it gives no reference of the direction of acceleration. In simple harmonic motion the direction of acceleration is always in a direction to that of the displacement.
Question: What is the location of the centre of mass of a
(i) Sphere, (ii) Cylinder, (iii) Ring, and (iv) Cube, each of uniform mass density.
Does the centre of mass of a body necessarily lie on the body?
In all the four cases, as the mass density is uniform, centre of mass is located at their respective geometrical centres.
No, it is not necessary that the centre of mass of a body should lie on the body. For example, in case of a circular ring, centre of mass is at the centre of the ring, where there is no mass.
Question: Define the following terms
(ii) Perfectly elastic body
(iii) Perfectly plastic body
(iv) Elastic limit
(vi) Hooke’s law
Elasticity: The property of a body to regain its original configuration when the deforming forces are removed.
Perfectly elastic body: A body by which regain its original configuration immediately and completely after the removal of the deforming force from it.
Perfectly plastic body: A body which does not regain its original configuration at all on the removal of deforming force, howsoever small the deforming force may be is called perfectly plastic body.
Elastic limit: It is the upper limit of deforming force up to which, if deforming force is removed, the body regains its original form completely and beyond which if deforming force is increased, the body loses its property of elasticity and gets permanently deformed.
Strain: When there a deforming force applied on a body, there is a change in configuration of the body. The body is said to be strained or deformed. The ratio of change in configuration to the orginal configuration is called strain.
Strain = (Change in configuration)/(Original configuration)
Hooke’s law: This laws states that within elastic limit, the stress developed is directly proportional to the strain produced in a body.
Stress ∝ Strain
Or Stress = E × Strain
Where E is a constant and is known as Modulus of elasticity of the material of the body.
Question: What are laws of limiting friction?
The laws of limiting friction are as follows:
(i) The magnitude of the force of limiting friction (F) between any two bodies in contact is directly proportional to the normal reaction (R) between them i.e.
(ii) The direction of the force of limiting friction is always opposite to the direction in which one body is at the verge of moving over the other.
(iii) The force of limiting friction is independent of the apparent area of contact, as long as the normal reaction between the two bodies in contact remains same.
(iv) The force of limiting friction between any two bodies in contact depends on the nature of material of the surfaces in contact and their roughness or smoothness.
Question: How will you distinguish between hardboiled egg and a raw egg by just spinning each on a table top?
The egg which spins at a slower rate shall be a raw egg because in a raw egg, liquid matter inside tries to get away from the axis of rotation. Therefore, its moment of inertia I increase. As, τ = I a = constant, therefore, a decreases i.e. raw egg will spin smaller angular acceleration
Question: The spin angular velocity of a star is greatly enhanced when it collapses under gravitational pull and becomes a neutron star. Explain the reason?
On collapsing under gravitational pull, the size of the star decreases. Therefore, its moment of inertia decreases. As angular momentum (L = I) is conserved, and I decreases, therefore, spin angular velocity increases.
Question: What are conservative and non-conservative forces? Give examples?
Conservative forces: A force is said to be conservative if work done by or against the force in moving a body depends on the initial and final positions of the body and not on the nature of the path followed between the initial and final positions. This means, work done by or against a conservative force in moving body over any path between fixed initial and final position will be the same.
Example: Gravitational force, electrostatic force.
Non-conservative force: A force is said to be non-conservative, if work done by or against the force in moving a body from one position to another, depends on the path followed between these two positions.
Example: Frictional force.
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