Students must start practicing the questions from CBSE Sample Papers for Class 12 Physics with Solutions Set 11 are designed as per the revised syllabus.
CBSE Sample Papers for Class 12 Physics Set 11 for Practice
Time Allowed: 3 Hours
Maximum Marks: 70 Marks
General Instructions:
- There are 35 questions in all. All questions are compulsory.
- This question paper has five sections: Section A, Section B, Section C, Section D and Section E. All the sections are compulsory.
- Section A contains eighteen MCQ of 1 mark each, Section B contains seven questions of two marks each, Section C contains five questions of three marks each, section D contains three long questions of five marks each and Section E contains two case study-based questions of 4 marks each.
- There is no overall choice. However, an internal choice has been provided in section B, C, D and E. You have to attempt only one of the choices in such questions.
- Use of calculators is not allowed.
Section – A (18 Marks)
Question 1.
What is dipole moment of an electric dipole? [1]
(a) \(\vec{p}=q .2 \vec{d}\)
(b) \(\vec{p}=q \cdot \vec{d}\)
(c) \(\vec{p}=2 q \cdot \vec{d}\)
(d) \(\vec{p}=q \cdot \frac{\vec{d}}{2}\)
Question 2.
How will a free electron at rest move in an electric field? [1]
(a) In same direction
(b) In opposite direction
(c) In perpendicular direction
(d) None of these
Question 3.
How we should connect a voltmeter across a resistance if we have to measure the potential difference across the resistance in an electric circuit? [1]
(a) In parallel
(b) In series
(c) Both (a) and (b)
(d) None of these
Question 4.
According to Bohr model of hydrogen atom, what is the angular momentum of an orbiting electron?
(a) \(\frac{n^2 h^2}{2 \pi}\)
(b) \(\frac{n h^2}{2 \pi}\)
(c) \(\frac{n h}{2 \pi}\)
(d) \(\frac{n^2 h}{2 \pi}\)
Question 5.
The equation of gauss law in magnetism is given by: [1]
(a) \(\int A . d B\) = 0
(b) \(\oint \mathrm{B}^2 \cdot d \mathrm{~A}\) = 0
(c) \(\oint_v \mathrm{~B} \cdot d \mathrm{~A}\) = 0
(d) \(\oint_s B_{.} d A\) = 0
Question 6.
Predict the direction of the induced current in metal rings 1 and 2 when current I in the wire is steadily decreasing? [1]
(a) Clockwise, Anticlockwise
(b) Anticlockwise, Clockwise
(c) In perpendicular direction
(d) No current induced
Question 7.
What is the de-Broglie wavelength associated with a ball of mass 150 g travelling at 30 m/s? [1]
(a) 1.274 × 10-34 m
(b) 1.472 × 10-34 m
(c) 1.427 × 10-34 m
(d) 1.247 × 10-34 m
Question 8.
Which of the following has the shortest wavelength: [1]
(a) x-rays
(b) ultraviolet (UV) rays
(c) microwaves
(d) Infrared waves
Question 9.
Which of the following lens has negative power? [1]
(a) Converging lens
(b) Bi-focal lens
(c) Diverging lens
(d) Both (a) and (c)
Answer:
Question 10.
In energy band, highest energy level occupied by electron at 0 K is known as: [1]
(a) Fermi level
(b) Fermi energy
(c) Valance level
(d) Conduction band
Question 11.
At what temperature given semiconductor would behave like a perfect insulator. [1]
(a) 273 K
(b) 40 K
(c) 0 K
(d) – 4 K
Question 12.
The diode current changes by 5 mA when the voltage drop across a p-n junction diode is raised from [1]
(a) 20Ω
(b) 50Ω
(c) 10Ω
(d) 80Ω
Question 13.
Two point charges 4Q and Q are separated by 1 m as shownn in figure. At what point on the line joining the charges, is the electric field intensity zero? [1]
(a) 2 m
(b) \(\frac{1}{3}\) m
(c) 4 m
(d) \(\frac{2}{3}\) m
Question 14.
Two metallic wires of the same material have the same length but cross-sectional area is in the ratio 1:2. If they are connected in series, what is the drift velocities of electrons in the two wires. [1]
(a) 1 : 2
(b) 2 : 1
(c) 4 : 1
(d) 1 : 4
Answer:
Question 15.
The relation between rms value and peak value of current is: [1]
(a) I0 = \(\sqrt{2}\) Irms
(b) Irms = 2 I0
(c) Irms = \(\sqrt{2}\) I0
(d) I0 = 2 Irms
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true and R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Question 16.
Assertion (A): If we increase the distance between two parallel plates of a parallel plate capacitor, then its capacitance decreases. [1]
Reason (R): Capacitance of a parallel plate capacitor is inversely proportional to the distance between two plates.
Question 17.
Assertion (A): Electric field lines due to positive charge are along radially outward direction from the charge. [1]
Reason (R): Positive charge repels another positive charge.
Question 18.
Assertion (A): In Young’s double slit experiment, interference pattern disappears when one of the slit is closed. [1]
Reason (R): Interference occurs due to superposition of light wave from two coherent sources.
Section – B (14 Marks)
Question 19.
An inductor L of reactance XL is connected in series with a bulb B to an AC source as shown in the figure: [2]
Briefly explain how does the brightness of the bulb change when:
(A) number of turns of the inductor is reduced.
(B) a capacitor of reactance XC = XL is included in series in the same circuit.
Question 20.
The energy of a charged particle travelling through a constant magnetic field remains constant. Why? [2]
Answer:
Question 21.
The oscillating electric field of an electromagnetic wave is given by: [2]
E = 30 sin[2 × 1011 t + 300π X] Vm-1
(A) Obtain the value of the wavelength of the electromagnetic wave.
(B) Write down the expression for the oscillating magnetic field.
Question 22.
Draw a ray diagram for the formation of image in a compound microscope. [2]
OR
Draw the intensity pattern for single slit diffraction and double slit interference.
Question 23.
A proton and an electron have same kinetic energy. Which one has smaller de-Broglie wavelength and why? [2]
OR
Show that the nuclear density in a given nucleus is independent of mass number A.
Question 24.
From the following figure, calculate: [2]
(A) Threshold frequency
(B) Work function for photoelectric effect in sodium.
Question 25.
How does the fringe width of interference fringes change, when the whole apparatus of Young’s double slit experiment is kept in a liquid of refractive index 1.3? [2]
Section – C (15 Marks)
Question 26.
A List in tabular form the differences between an electric motor and a generator. [3]
OR
(A) Prove that an ideal capacitor in a pure capacitive AC circuit does not dissipate power.
(B) A light bulb is rated 150 W for 220 V AC supply of 60 Hz. Calculate the rms current through the bulb.
Question 27.
Plot a graph showing the variation of stopping potential with the frequency of incident radiation for two different photosensitive materials having work functions W1 and W2 (W1 > W2). On what factors does the; [3]
(A) slope and
(B) intercept of the lines depend?
OR
(A) Discuss the properties of nuclear force.
(B) State the reason, why heavy water is generally used as a moderator in a nuclear reactor?
Question 28.
(A) State Kirchhoff’s loop law. [3]
(B) Draw a plot showing the variation of resistivity of a:
- Conductor
- Semiconductor, with increase in temperature.
Question 29.
(A) Distinguish between nuclear fission and fusion. Show how in both these processes energy is released? [3]
(B) Why is the binding energy per nucleon found to be constant for nuclei in the range of mass number falling in between 30 and 170?
Question 30.
Explain the Biot-Savarts law. What is the magnetic field at the centre of an n-turn circular coil carrying current, I? [3]
Section – D (15 Marks)
Question 31.
Two charges -q and +q are located at points (0,0,- a) and (0,0, a) respectively. [5]
(A) What is the electrostatic potential at the points?
(B) Obtain the dependence of potential on the distance r of a point from the origin when, \(\frac{r}{a}\) >>1.
(C) How much work is done in moving a small test charge from the point from the point (5,0,0) to (- 7,0,0) along the x-axis? Does the answer change if the path of the test charge between the same points is not along the x-axis?
OR
(A) Define the SI unit of capacitance.
(B) Write two properties of equipotential surfaces.
(C) (i) A capacitor of unknown capacitance is connected across a battery of V volts.The charge stored in it is 300 µC. When potential across the capacitor is reduced by 100 V, the charge stored in it becomes 100 v. Calculate the potential V and the unknown capacitance.
(ii) What will be the charge stored in the capacitor if the voltage applied had increased by 100 V?
Question 32.
Answer the following questions:
(A) in a single slit diffraction experiment, the slit width is doubled from its initial width. What effect does this have on the width and intensity of the central diffraction band?
(B) In a double-slit experiment, how is diffraction from each slit connected to the interference pattern?
(C) A luminous spot is observed at the centre of the obstruction’s shadow when a tiny circular barrier is put in the path of light from a distant source. Why is this so?
(D) A 7-meter-high partition wall separates two students in a 10-meter-high room.
If both light and sound waves can bend around obstructions, how come the students can’t see each other yet being able to talk easily?
(E) Ray optics is predicated on the idea that light follows a straight line. This assumption is disproved by diffraction effects (seen when light propagates through small apertures/slits or around small obstructions). Despite this, the ray optics assumption is often utilised in optical equipment to comprehend position and other picture aspects.
OR
(A) Name the em waves which are used for the treatment of certain forms of cancer. Write their frequency range.
(B) Thin ozone layer on top of stratosphere is crucial for human survival. Why?
(C) Why is the amount of the momentum transferred by the em waves incident on the surface so small?
(D) W the earth did not have atmosphere, would its average surface temperature be higher or lower than what ¡t Is now? Explain.
(E) An EM wave exerts pressure on the surface on which It is incident Justify.
Question 33.
(A) Describe Faraday’s law. [5]
(B) The current flowing through an inductor of self-inductance L is continuously increasing. Plot a graph showing the variation of:
- magnetic flux versus the current
- induced emf versus \(\frac{d l}{d t}\).
- magnetic potential energy stored versus the current.
OR
Predict the direction of Induced current in the situations described In the following figures.
Section – E (8 Marks)
Question 34.
The potential barrier in a p-n junction diode is the barrier that requires more force for the charge to cross. In other terms, the potential barrier is the barrier in which the charge carrier is blocked by the obstructive force.
When we bring a p-type semiconductor into close contact with an n-type semiconductor, we get a p-n junction with a barrier potential of 0.4 V and a depletion area width of 4.0 × 10-7 m. As indicated in the picture, this p-n junction is forward biased with a battery of voltage 3 V and minimal internal resistance, in series with a resistor of resistance R, ideal millimeter, and key K. When the key is tapped, a 20 mA current is flowing through the diode.
(A) When the p-n junction is unbiased, then calculate the strength of the electric field at the depletion area. [1]
(B) Find the resistance of resistor, R. [1]
(C) What is the Potential Barrier? If the potential barrier voltage is V0. When a voltage V is delivered to the input, when will the barrier completely disappear?
OR
If an electron with a speed of 4.0 × 105 ms-1 approaches the p-n junction from the n-side, than calculate its speed upon entering the p-side. [2]
Question 35.
Electromagnetic radiation is an electric and magnetic disturbance traveling through space at the speed of light (2.998 × 108 m/s). It contains neither mass nor charge but travels in packets of radiant energy called photons, or quanta.
Examples of em radiation include radio waves and microwaves, as well as infrared, ultraviolet, gamma, and x-rays. Some sources of EM radiation include sources in the cosmos (e.g., the sun and stars), radioactive elements, and manufactured devices. EM exhibits a dual wave and particle nature.
Classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields.
(A) Give the relation between the speed of an electromagnetic wave and speed of light. [1]
(B) Which waves are related to tele-communication? [1]
(C) What is the nature of electromagnetic wave? [2]
OR
Which field oscillates in em wave?