ISC Physics 2013 Class-12 Solved Previous Year Question Paper for practice. Step by step Solutions of Part I and II with section-A, B and C. Visit official website CISCE for detail information about ISC Class-12 Physics.

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## Previous Year Question Paper ISC Physics 2013 Class-12 Solved

Part – I

Section-A Part – II

Section-B Part – II

Section-C Part – II

### Previous Year Question Paper ISC Physics 2013 Class-12 Solved

Maximum Marks: 70
Time allowed: 3 hours

• Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time.
• Answer all questions in Part I and six questions from Part II, choosing two questions from each of the Sections A, B and C.
• All working, including rough work, should be done on the same sheet as, and adjacent to, the rest of the answer.
• The intended marks for questions or parts of questions are given in brackets [ ].
• Material to be supplied: Log tables including Trigonometric functions
• A list of useful physical constants is given at the end of this paper.

### Part – I (20 Marks)(Answer all questions)

( ISC Physics 2013 Class-12 Solved Previous Year Question Paper )

Question 1.
(A) Choose the correct alternative (a), (b), (c) or (d) for each of the questions given below : 
(i) Relative permittivity of water is 81. If ∈w and ∈0 are permitivities of water and vacuum respectively, then.
(a) $\epsilon_{0}=9 \epsilon_{w}$
(b) $\epsilon_{0}=81 \epsilon_{w}$
(c) $\epsilon_{w}=9 \epsilon_{0}$
(d) $\epsilon_{w}=81 \epsilon_{0}$

ii) Five resistors are connected as shown in figure. The effective resistance i.e., equivalent resistance between the points A and B is :
(a) 4 Ω
(b) 5 Ω
(c) 15 Ω
(d) 20 Ω (iii) The Biot Savart’s Law in vector form is:
(a) $\overline{\delta \mathrm{B}}=\frac{\mu_{0}}{4 \pi} \frac{d l(\overrightarrow{\mathrm{I}} \times \vec{r})}{r^{3}}$
(b) $\overline{\delta \mathrm{B}}=\frac{\mu_{0}}{4 \pi} \frac{\mathrm{I}(\overrightarrow{d l} \times \vec{r})}{r^{3}}$
(c) $\overline{\delta \mathrm{B}}=\frac{\mu_{0}}{4 \pi} \frac{\mathrm{I}(\vec{r} \times \overrightarrow{d l})}{r^{3}}$
(d) $\overline{\delta \mathrm{B}}=\frac{\mu_{0}}{4 \pi} \frac{\mathrm{I}(d \vec{l} \times \vec{r})}{r^{2}}$

(iv) In an astronomical telescope of refracting type :
(a) Eyepiece has greater focal length
(b) Objective has greater focal length
(c) Objective and eyepiece have equal focal length
(d) Eyepiece has greater aperture than the objective.

(v) The particles which cannot be accelerated by a cyclotron or a Van de Graff generator are :
(a) Alpha particles
(b) Beta particles
(c) Neutrons
(d) Protons 

(B) Answer all questions given below briefly and to the point:
(i) A large hollow metallic sphere has a positive charge of 35.4 μC at its center. Find how much electric flux emanates from the sphere.

(ii) A current ‘I’ flows through a metallic wire of radius ‘r’ and the free electrons in it drift with a velocity vd. Calculate the drift velocity of the free electrons through the wire of the same material, having double the radius, when same current flows through it.

(iii) Name any one instrument which works on the principle of tangent law in magnetism.

(iv) State the SI unit of magnetic dipole moment.

(v) Alternating current flowing through a certain electrical device leads over the potential difference across it by 90°. State whether this device is a resistor, capacitor or an inductor.

(vi) What is the shape of the wave front diverging from a point source of light ?

(vii) The critical angle for a given transparent medium and air is ic. A ray of light travelling in air is incident on this transparent medium at an angle of incidence equal to the polarising angle ip. What is the relation between the two angles ic and ip ?

(viii) Find the focal length and nature of a lens whose optical power is – 5D.

(ix) What is Modulation ? Explain in brief.

(x) What are the dark lines seen in the solar spectrum called ?

(xi) What is the relation between wavelength and momentum of moving particles ?

(xii) Name the series of lines in the hydrogen spectrum which lies in the ultra-violet region.

(xiii) Fill in the blank in the given nuclear reaction: $\begin{array}{r}{+\frac{27}{13} \mathrm{Al} \longrightarrow_{12}^{25} \mathrm{Mg}+\frac{4}{2} \mathrm{He}} \\ {13}\end{array}$

(xiv) Give an example where energy is converted into matter.

(xv) To convert a pure semiconductor into n-type semiconductor, what type of impurity is added to it ?
(A)

(i) (d)
(ii) (a)
(iii) (b)
(iv) (b)
(v) (c)

(B)

(i) Here, q = 35.4 x 10-6 C
By Gauss Law, $\phi=\frac{q}{\epsilon_{0}}=\frac{35 \cdot 4 \times 10^{-6}}{8 \cdot 85 \times 10^{-12}}=4 \times 10^{6} \mathrm{Nm}^{2} \mathrm{C}^{-1}$

(ii) We know, (iv) The SI unit of magnetic dipole moment is Coulomb-meter (Cm).
(v) The device is a capacitor.
(vi) Spherical.
(vii) If ip is the polarising angle and n the refractive index of the medium, then n = tan ip If ic is the critical angle,then (viii) We know that, $f_{m}=\frac{1}{\mathrm{D}}=-\frac{1}{5}=-0 \cdot 2 \mathrm{m}=-20 \mathrm{cm}$
∴ – ve sign shows that the lens is concave.

(ix) The audio signal cannot be transmitted efficiently as such. Modulation is the process of modifying some characteristic of a high frequency carrier wave (amplitude, frequency or phase) in accordance with the instantaneous value of the amplitude of modulating signal. The modulating signal is then transmitted across space.

(x) Dark lines has also called Fraunhoffer’s lines.

(xi) The required relation is λ = h/p where λ = wavelength and p the momentum of the particle and h = Planck’s constant.

(xii) The series emitted in the hydrogen spectrums in ultra-violet region is called the “Lyman Series.”

(xiii) The missing particle is $_{1}^{2} \mathrm{H}$

(xiv) In pair production. It is materialization of energy.

(xv) To get n-type semiconductor, the semiconductor is doped with an impurity like antimony.

Section-A Part – II (20 Marks)

(Answer six questions in this part, choosing two questions from each of the Sections A, B and C)

### ( ISC Physics 2013 Class-12 Solved Previous Year Question Paper )

Question 2.
(a)

(i) Write an expression (derivation not required) for intensity’ of electric field in :
(1) Axial position.
(2) Broad side position of an electric dipole, in terms of its length (2a) dipole moment (p) and distance (r).
(ii) What is the ratio of these two intensities i.e., E1 : E2, for a short electric dipole ? 

(b) Three capacitors C1 = 6 μF, C2 = 12 μF and C3 = 20 μF are connected to a 100 V battery, as shown in figure alongside: Calculate:
(i) Charge on each plate of capacitor C1.
(ii) Electrostatic potential energy stored in capacitor C3. 

(c) ‘n’ cells, each of emf’e and internal resistance ‘r’ are joined in series to form a row. ‘m’ such rows are connected in parallel to form a battery of N = mn cells. This battery is connected to an external resistance ‘R’. 
(i) What is the emf of this battery and how much is its internal resistance ?
(if) Show that current ‘I’ flowing through the external resistance R’ is given by : $\mathrm{I}=\frac{\mathrm{N} e}{m \mathrm{R}+n r}$    Read Next 👇 Click on Page Number Given Below 👇

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