 # CBSE Class 12 Physics Last 5 + 1 Years’ Very Long Answer Type Questions

Get CBSE class 12 Physics previous 5 + 1 years’ very long answer type questions. These questions are important for CBSE Class 12 Physics board exam 2017. CBSE class 12 Physics previous 5 + 1 years’ very long answer type questions are available in this article.

As per latest examination pattern, 4 long answer type questions will be asked in CBSE class 12 Physics exam 2017. Out of 4 questions, 1 will be (value based question) of four marks and rest 3 will be of five marks.

Before the year 2015, the examination pattern of CBSE Class 12 Physics board exam was quite different.

However, in order to understand the level of questions which can be asked in CBSE class 12 Physics exam 2017, students of CBSE class 12 must go through these previous year questions.

CBSE Class 12 Physics Sample Paper 2017

The solutions of these questions are available in CBSE Class 12th Solved Previous Years' Papers (Last 5+ 1 years') PCM - eBook

Questions from previous year papers are given below:

 CBSE Class 12 Physics Board Exam 2016: Very Long Answer Type Questions (4 Marks & 5 Marks) Q. Ram is a student of class X in a village school. His uncle gifted him a bicycle with a dynamo fitted in it. He was very excited to get it. While cycling during night, he could light the bulb and see the objects on the road. He, however, did not know how this device works. He asked this question to his teacher. The teacher considered it an opportunity to explain the working to the whole class. Answer the following questions: (a) State the principle and working of a dynamo. (b) Write two values each displayed by Ram and his school teacher. CBSE Class 12 Syllabus 2017 Q. (i) Use Gauss's law to find the electric field due to a uniformly charged infinite plane sheet. What is the direction of field for positive and negative charge densities? (ii) Find the ratio of the potential differences that must be applied across the parallel and series combination of two capacitors C1 and C2 with their capacitances in the ratio 1:2 so that the energy stored in the two cases becomes the same. OR Q. (i) If two similar large plates, each of area A having surface charge densities + σ and ‒σ are separated by a distance d in air, find the expressions for (a) field at points between the two plates and on outer side of the plates. Specify the direction of the field in each case. (b) the potential difference between the plates. (c) the capacitance of the capacitor so formed. (ii) Two metallic spheres of radii R and 2R are charged so that both of these have same surface charge density σ. If they are connected to each other with a conducting wire, in which direction will the charge flow and why? CBSE Class 12 Physics Sample Paper 2017 Q. (i) Draw a labelled diagram of a step-down transformer. State the principle of its working. (ii) Express the turn ratio in terms of voltages. (iii) Find the ratio of primary and secondary currents in terms of turn ratio in an ideal transformer. (iv) How much current is drawn by the primary of a transformer connected to 220 V supply when it delivers power to a 110 V ‒ 550 W refrigerator? OR Q. (a) Explain the meaning of the term mutual inductance. Consider two concentric circular coils, one of radius r1 and the other of radius r2 (r1 R and r < R (r being the distance from the centre of the shell). Q. Using Bhor’s postulates derive the expression for the frequency of radiation emitted when electron in hydrogen atom undergoes transition from higher energy state (Quantum number ni) to the lower. (nf). When electron in hydrogen atom jumps from state ni = 4 to nf  = 3, 2, 1, identify the spectral series to which the emission lines below. OR (a) Draw the plot of binding energy per nuclear (BE/A) as a function of mass number A. Write two important conclusions that can be drawn regarding the nature of nuclear force? (b) Use this graph to explain the release of energy in both the processes of nuclear fusion and fusion? (c) Write the basic nuclear process of neutron undergoing β – decay. Why is the detection of neutrinos found very difficult? (b) Use this graph to explain the release of energy in both the processes of nuclear fusion and fusion? (c) Write the basic nuclear process of neutron undergoing β – decay. Why is the detection of neutrinos found very difficult? CBSE Class 12 Physics Board Exam 2012: Long Answer Type Questions (5 Marks) Q. (a) In Young's double slit experiment, derive the condition for (i) constructive interference and (ii) destructive interference at a point on the screen. (b)A beam of light consisting of two wavelength, 800 nm and 600 nm is used to obtain the interference fringes in a Young's double slit experiment on a screen placed 1.4 m away. If the two slits are separated by 0.28 mm, calculate the least distance from the central bright maximum where the bright fringes of the two wavelengths coincide. OR (a) How does an unpolarized light incident on a Polaroid get polarized? Described briefly, with help of a necessary diagram, the polarization of light by reflection from a transparent medium. (b)Two Polaroid’s ‘A’ and ‘B’ are kept in crossed position. How should a third Polaroid ‘C’ be placed between them so that the intensity of polarized light transmitted by Polaroid B reduces to 1/8th of the intensity of unpolarized light incident on A? Q. (a) Describe briefly, with the help of a diagram, the role of the two important processes involved in the formation of a p-n junction. (b)Name the device which is used as a voltage regulator. Draw the necessary circuit diagram and explain its working. OR (a) Explain briefly the principle on which a transistor-amplifier works an a oscillator. Draw the necessary circuit diagram and explain its working. (b)Identify the equivalent gate for the following circuit and write its truth table. Q. (a)Write the expression for the force, F, acting on a charged particle of charge ‘q’, moving with a velocity v in the presence of both electric field E and magnetic field B. Obtain the condition under which the particle moves undeflected through the fields. (b)A rectangular loop of size l × b carrying a steady current I is placed in uniform magnetic field B. Prove that the torque τr acting on the loop is given by τ = m × B, where m is the magnetic moment of the loop. OR (a) Explain, giving reasons, the basic difference in converting a galvanometer into (i) a voltmeter and (ii) an ammeter. (b)Two long straight parallel conductors carrying steady currents I1 and I2 are separated by a distance ‘d’. Explain briefly, with the help of a suitable diagram, how the magnetic field due to one conductor acts on the other. Hence deduce the expression for the force acting between the two conductors. Mention the nature of this force. CBSE Class 12 Physics Board Exam 2011: Long Answer Type Questions (5 Marks) Q. (a) State the principle of the working of a moving coil galvanometer, giving its labeled diagram. (b) "Increasing the current sensitivity of a galvanometer may not necessarily increase its voltage sensitivity." Justify this statement. (c) Outline the necessary steps to convert a galvanometer of resistance RG into an ammeter of a given range. OR (a) Using Ampere's circuital law, obtain the expression for the magnetic field due to a long solenoid at a point inside the solenoid on its axis. (b) In what respect is a toroid different from a solenoid? Draw and compare the pattern of the magnetic field lines in the two cases. (c) How is the magnetic field inside a given solenoid made strong? Q. State the working of AC generator with the help of a labeled diagram. The coil of an a.c. generator having N turns, each of area A, is rotated with a constant angular velocity ω. Deduce the expression for the alternating EMF generated in the coil. What is the source of energy generation in this device? OR (a) Show that in an AC circuit containing a pure inductor, the voltage is ahead of current by p/2 in phases. (b) A horizontal straight wire of length L extending from east to west is falling with speed v at right angles to the horizontal component of Earth's magnetic field B. (i) Write the expression for the instantaneous value of the EMF induced in the wire. (ii) What is the direction of the EMF? (iii) Which end of the wire is at the higher potential? State the importance of coherent sources in the phenomenon of interference. In Young's double slit experiment to produce interference pattern, obtain the conditions for constructive and destructive interference. Hence deduce the expression for the fringe width. How does the fringe width get affected, if the entire experimental apparatus of Young is immersed in water? OR (a) State Huygens Principle. Using this principle explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a narrow beam coming from a monochromatic source of light is incident normally. (b) Show that the angular width of the first diffraction fringe is half of that of the central fringe. (c) If a monochromatic source of light is replaced by white light, what change would you observe in the diffraction pattern?

CBSE Class 12th Solved Previous Years' Papers (Last 5+ 1 years') PCM - eBook