# CBSE Class 12 Physics Practice Paper 2017: Set – II

CBSE Practice Paper for class 12th Physics is available in this article. This practice paper is based on latest examination pattern and important for coming CBSE class 12 Physics exam 2017.  CBSE Class 12 Physics paper is available here. All the questions of this practice paper are based on the concepts which have been frequently asked in previous year question paper of CBSE Class 12 Physics board exams.
This practice paper is based on latest CBSE Class 12 Physics Syllabus 2017. The pattern of this practice paper is almost similar to Class 12 Physics Sample Paper issued by CBSE for CBSE board exam 2017.
With this practice paper students of CBSE class 12 can easily analyze their preparation level of CBSE Class 12 Physics board exam 2017.
All the questions of this practice papers are very important for CBSE Class 12 Physics Board Exam 2017

Time allowed: 3 hours                                                                                               Maximum Marks: 70

General Instructions:

(a) All questions are compulsory.

(b) There are 26 questions in all. Question number 1 to 5 carry one mark each, question number 6 to 10 carry two marks each, question number 11 to 22 carry three marks each, question number 23 carry four marks and question number 24 to 26 carry 5 marks each.

(c) There is no overall choice. However, internal choices have been provided in some questions.

SECTION A

Question1. If a sphere S encloses a charge Q. There is a larger concentric sphere S’ with no additional charge between S and S’. What is the ratio of electric flux through S and S’?

Question2. Can there be a potential difference between two adjacent conductors carrying the same charge?

Question3. What is a wattless current?

Question4. Which of the following have shortest wavelength and lowest frequency?

Ultraviolet Rays, Infrared Rays, Microwaves, X-Rays

Question5. Define current sensitivity of a galvanometer?

CBSE Class 12 Physics Syllabus 2017

SECTION B

Question6. Write two ways by which the range of transmission can be increased?

Question7. Using the data given below, state as to which of the given lenses will you prefer to use as an eyepiece, and an objective, to construct an astronomical telescope. Give reason to support your answer.

 Lens Focal length Aperture A 100 cm 10 cm B 100 cm 5 cm C 10 cm 2 cm D 5 cm 2 cm

OR

Question7: The following data was recorded for values of object distance and the corresponding values of image distance in the experiment on study of real image formation by a convex lens of power + 5 D. One of these observations is incorrect. Identify this observation and give reason for your choice.

 Serial Number (1) (2) (3) (4) (5) (6) Object distance (cm) 25 30 35 45 50 55 Image distance (cm) 97 61 37 35 32 30

Question8: Find the radius of the path of an electron moving at a speed of 3 × 107 ms‒1 in a magnetic field of 6 × 10‒ 4 T perpendicular to it? Also, find its frequency.
Give, mass of electron = me = 9 × 10‒31 kg and charge on it = 1.6 × 10‒19 C).

Question9: What is meant by ‘half-life’ of a radioactive element? What percentage of a given mass of a radioactive substance will be left undecayed after four half lives?

Question10: Two cells of E.M.F. 10 V and 2 V and internal resistances 10 Ω and 5 Ω respectively, are connected in parallel as shown in the figure given below. Find the effective voltage across R.

SECTION C

Question11: (i) In a meter bridge shown in the figure given below, the balance point is found to be 39.5 cm from end X, when the resistance in the right arm is 12.5 Ω. Find unknown resistance R.

(ii) What will happen to balance point when resistance R and12.5 Ω are interchanged.

(iii) Why are resistors in a meter bridge are connected by thick copper strips?

OR

Question11: In the figure given below, a long uniform potentiometer wire XY having a constant potential gradient along its length. The two primary cells are connected and the reading of the null points is obtained from point X as shown in the figure.

Calculate (i) Ratio E1/E2 (ii) position of the null point for the cell E1.

Question12: A glider with 20 m long metallic wing spread is flying at 250 ms‒1 straight south parallel to the earth’s surface. The earth’s magnetic field has a horizontal component of 2 × 10‒5 Wb m‒2 and the dip angle is 60o. Find the value of induced emf across the tips of the wing.

Question13: (i) The ground state energy of hydrogen atom is –13.6 eV. What are the kinetic and potential energies of the electron in this state?

(ii) Using de Broglie’s hypothesis, explain with the help of a suitable diagram, Bohr’s second postulate of quantization of energy levels in a hydrogen atom.

Question14: Arrange the following electromagnetic radiations in ascending order of their frequencies:
(i) Microwaves
(iii) X-rays
(iv) Gamma rays
Write two uses of any two of these.

Question15: Draw a plot showing the variation of binding energy per nucleon versus the mass number A. Explain with the help of this plot the release of energy in the processes of nuclear fission and fusion.

Question16: (a) What are characteristic properties of an intrinsic semiconductor?

(b)The following figure shows the input waveforms (A, B) and the output wavefrom (Y) of a gate. Identify the gate, write its truth table and draw its logic symbol.

Question17: Write two basic modes of communication. Explain the process of amplitude modulation. Draw a schematic sketch showing how amplitude modulated signal is obtained by superposing a modulating signal over a sinusoidal carrier wave.

Question18: Light of wavelength 2000 Å falls on a metal surface of work functions 4.2 eV. What is the kinetic energy (in eV) of the fastest electrons emitted from the surface?

(i) What will be the change in the energy of the emitted electrons if the intensity of light with same wavelength is doubled?

(ii) If the same light falls on another surface of work functions 6.5 eV, what will be the energy of emitted electrons?

Question19: What is the effect on the interference fringes in a Young’s double slit experiment when

(i) the separation between the two slits in decreased?

(ii) the width of the source slit is increased?

(iii) the monochromatic source is replaced by a source of white light?

Question20: With a circuit diagram, explain how a Zener diode can be used as a voltage regulator.

Question21: Consider two hollow concentric spheres, S1 and S2, enclosing charges 2Q and 4Q respectively as shown in the figure.

(i) Find out the ratio of the electric flux through them.

(ii) How will the electric flux through the sphere S1 change if a medium of dielectric constant 'εr' is introduced in the space inside S1 in place of air ? Deduce the necessary expression.

Question22: If N drops of same size each having the same charge, coalesce to form a bigger drop. What is change in the charge, capacity and potential of the bigger drop with respect to smaller drop?

SECTION D

Question23: Amit is a resident of Tamil Nadu was all set to leave everything and shift to another place in view of the decision of Government to start nuclear thermal power plant at Tamil Nadu. His granddaughter Rashi, a science student was really upset on the ignorant decision of her grandfather. She could finally convince him not to shift, since adequate safety measures to avoid any nuclear mishap have already been taken by the Government before starting nuclear thermal power plants.

(i) What is the value displayed by Rashi in convincing her grandfather?

(ii) What is the principle behind working of nuclear reactor?

(iii) What are the main components of nuclear reactor?

(iv) Why is heavy water used as moderator?

SECTION E

Question24: (a) Derive an expression for the torque experienced by an electric dipole kept in a uniformly electric field.

(b) Calculate electric potential energy of the system of charges placed on the vertices of a triangle (as shown in the figure given below). Here q =1.6 × 10-19 C.

OR

Question24: (a) How will the (i) energy stored and (ii) the electric field inside the capacitor be affected when it is completely filled with a dielectric material of dielectric constant ‘K’?

(b) Obtain the equivalent capacitance of the network given below. For a supply of 300 V, determine the charge and voltage across C4 .

Question25: Derive an expression for the impedance of a series LCR circuit connected to an AC supply of variable frequency and hence find the expression to find the value of resonant frequency. Explain briefly how the phenomenon of resonance in the circuit can be used in the tuning mechanism of a radio or a TV set.

OR

Question25: (a) What do you understand by root mean square value of alternating current? Derive an expression to show that the root mean square value of alternating current is 0.707 times the value of alternating current.

(b) Find the virtual value of alternating current shown in figure given below

Question26: Draw a labelled diagram of compound microscope and show the how image of a linear object is formed in the same diagram. A compound microscope uses an objective lens of focal length 4 cm and eyepiece lens of focal length 10 cm. An object is placed at 6 cm from the objective lens. Calculate the magnifying power of the compound microscope. Also calculate the length of the microscope.

OR

Question26: (a) Derive an expression for the Prism formula?

(b) One face of a prism with a refracting angle of 30° is coated with silver. A ray incident on another face at an angle of 45° is refracted and reflected from the silver coated face and retraces its path. Find the refractive index of the material of the prism.

CBSE Class 12 Biology Solved Practice Paper 2017

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