Q1
mcq
1 mark
An isolated conductor, with a cavity, has a net charge +Q. A point charge +q is inside the cavity. The charges on the cavity wall and the outer surface are respectively :
- A. 0 and Q
- B. q and Q q
- C. q and Q + q
- D. 0 and Q q
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Q2
mcq
1 mark
A proton is taken from point P1 to point P2, both located in an electric field. The potentials at points P1 and P2 are 5 V and + 5 V respectively. Assuming that kinetic energies of the proton at points P1 and P2 are zero, the work done on the proton is :
- A. 1·6 10 18 J
- B. 1·6 10 18 J
- C. Zero
- D. 0·8 10 18 J
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Q3
mcq
1 mark
A 2.0 cm segment of wire, carrying 5.0 A current in positive y-direction lies along y-axis, as shown in the figure. The magnetic field at a point (3 m, 4 m, 0) due to this segment (part of a circuit) is :
- A. (0.12
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Q4
mcq
Two thin long parallel wires, separated by a distance 'a', carry currents in opposite directions. The wires will :
- A. Repel each other with a force 2 2 0 2 a I, per unit length.
- B. Attract each other with a force 2 2 0 2 a I, per unit length.
- C. Attract each other with a force 2 a I2 0, per unit length.
- D. Repel each other with a force 2 a I2 0, per unit length.
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Q5
mcq
A current carrying circular loop of magnetic moment M is suspended in a vertical plane in an external magnetic field B such that its plane is normal to B. The work done in rotating this loop by 45 about an axis perpendicular to B is closest to :
- A. 0.3 MB
- B. 0.3 MB
- C. 1.7 MB
- D. 1.7 MB
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Q6
mcq
The mutual inductance of two coils C1 and C2 is 20 mH. In coil C1, the current changes from 4 A to zero in 0·2 s. If the resistance of coil C2 is 4, then the charge that flows through it per second will be :
- A. 4.0 C
- B. 1.5 C
- C. 0.05 C
- D. 0.1 C
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Q7
mcq
Consider a solenoid of length l and area of cross-section A with fixed number of turns. The self-inductance of the solenoid will increase if :
- A. both l and A are increased
- B. l is decreased and A is increased
- C. l is increased and A is decreased
- D. both l and A are decreased
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Q8
mcq
Electromagnetic waves with frequency 1.0 1018 Hz are known as :
- A. Infrared rays
- B. Ultraviolet rays
- C. X-rays
- D. Gamma rays
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Q9
mcq
A proton and an alpha particle having equal velocities approach a target nucleus. They come momentarily to rest and then reverse their directions. The ratio of the distance of closest approach of the proton to that of the alpha particle will be :
- A. 2 1
- B. 2
- C. 4 1
- D. 4
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Q10
mcq
The figure shows the variation of stopping potential V0 with frequency vof incident radiation, for three materials M1, M2 and M3 with work functions 1, 2 and 3 respectively. Then :
- A. 1 > 2 > 3
- B. 2 > 3 > 1
- C. 3 > 2 > 1
- D. 2 > 1 > 3
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Q11
mcq
An electron makes a transition from n = 2 level to n = 1 level in the Bohr model of a hydrogen atom. Its period of revolution :
- A. increases by 87.5%
- B. decreases by 87.5%
- C. increases by 43.75%
- D. decreases by 43.75%
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Q12
mcq
Si is doped with a pentavalent element. The energy required to set the additional electron free is about :
- A. 0.01 eV
- B. 0.05 eV
- C. 0.72 eV
- D. 1.1 eV
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Q13
mcq
Assertion (A) : In a semiconductor, the electrons in the conduction band have lesser energy than those in the valence band. Reason (R) : Donor energy level is just above the valence band in a semiconductor.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false and Reason (R) is also false.
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Q14
mcq
Assertion (A) : Photoelectric effect demonstrates the particle nature of light. Reason (R) : Photoelectric current is proportional to frequency of incident radiation.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false and Reason (R) is also false.
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Q15
mcq
Assertion (A) : A proton and an electron enter a uniform magnetic field B with the same momentum p such that p is perpendicular to B . They describe circular paths of the same radius. Reason (R) : In a magnetic field, orbital radius r is equal to pqB.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false and Reason (R) is also false.
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Q16
short answer
Assertion (A) : A convex lens, when immersed in a liquid, disappears. Reason (R) : The refractive indices of material of the lens and the liquid are equal.
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Q17
long answer
2 marks
What is meant by relaxation time of free electrons in a conductor ? Show that the resistance of a conductor can be expressed by R = ml / (ne^2τA), where symbols have their usual meanings.
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Q18
long answer
2 marks
Draw the circuit diagram of a Wheatstone bridge. Obtain the condition when no current flows through the galvanometer in it.
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Q18
short answer
2 marks
The magnifying power of an astronomical telescope is 24. In normal adjustment, distance between its two lenses is 150 cm. Find the focal length of the objective lens.
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Q19
short answer
2 marks
Write two points of difference between interference and diffraction of light.
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Q20
short answer
2 marks
Light of wavelength 500 nm is incident on caesium metal (work function 2.14 eV) and photoemission of electrons occurs. Calculate the (i) kinetic energy (in eV) of the fastest electrons and (ii) stopping potential for this situation. (Take hc = 1240 eV.nm)
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Q21
short answer
2 marks
Suppose a pure Si crystal has 5 x 10^28 atoms/m^3. It is doped by 1 ppm concentration of boron. Calculate the concentration of holes and electrons, given that ni = 1.5 x 10^16/m^3. Is the doped crystal n-type or p-type?
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Q22
long answer
3 marks
A battery of unknown emf E and internal resistance r is connected in a circuit as shown in the figure. When the key (K) is open, the voltmeter reads 10.0 V and ammeter reads 0 A. In the closed circuit, the voltmeter reads 6.0 V and ammeter reads 2.0 A. Calculate: (a) emf of the battery, (b) internal resistance of the battery (r), and (c) external resistance (R).
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Q23
long answer
3 marks
A rectangular loop of area A, carrying current I, is placed in a uniform magnetic field B. With the help of a suitable diagram, derive an expression, in vector form, for the torque acting on the loop.
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Q24
long answer
3 marks
Distinguish between reactance and impedance of an ac circuit. Show that an ideal inductor in an ac circuit does not dissipate any power.
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Q25
long answer
3 marks
In a vacuum, an electromagnetic wave has an electric field E = (6.3 N/C) [cos (1.5 rad/m) y + (4.5 x 10^8 rad/s) t]. (a) Find the wavelength and frequency of the wave. (b) Write an expression for the magnetic field of this wave.
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Q25
short answer
3 marks
The electric field in an electromagnetic wave in vacuum is given by : E = (6·3 N/C) [cos (1·5 rad/m) y + (4·5 108 rad/s) t] (a) Find the wavelength and frequency of the wave. (b) What is the amplitude of the magnetic field of the wave? (c) Write an expression for the magnetic field of this wave.
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Q26
long answer
3 marks
Use Bohr theory. Draw the energy level diagram of hydrogen atom showing its various spectral series.
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Q27
short answer
3 marks
(a) Define atomic mass unit (u). (b) Calculate the energy required to separate a deuteron into its constituent parts (a proton and a neutron). Given : m(D) = 2.014102 u, mH = 1.007825 u, mn = 1.008665 u
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Q28
long answer
3 marks
(a) Draw the circuit diagrams for obtaining the V I characteristics of a p-n junction diode. Explain briefly the salient features of the V I characteristics in (i) forward biasing, and (ii) reverse biasing.
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Q31
long answer
3 marks
(b) On the basis of energy band diagrams, distinguish between (i) an insulator, (ii) a semiconductor, and (iii) a conductor.
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The figure shows four pairs of parallel identical conducting plates, separated by the same distance 2.0 cm and arranged perpendicular to x-axis. The electric potential of each plate is mentioned. The electric field between a pair of plates is uniform and normal to the plates.
Q32
mcq
1 mark
For which pair of the plates is the electric field E along i?
- A. I
- B. II
- C. III
- D. IV
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Q33
mcq
1 mark
An electron is released midway between the plates of pair IV. It will :
- A. move along i at constant speed
- B. move along i at constant speed
- C. accelerate along i
- D. accelerate along i
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Q34
mcq
1 mark
Let V0 be the potential at the left plate of any set, taken to be at x = 0 m. Then potential V at any point (0 x 2 cm) between the plates of that set can be expressed as : where is a constant, positive or negative.
- A. V = V0 + x
- B. V = V0 + x2
- C. V = V0 + x1/2
- D. V = V0 + x3/2
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Q35
mcq
1 mark
Let the magnitudes of the electric fields between the plates I, II, III and IV be E1, E2, E3 and E4 respectively. Then :
- A. E1 > E2 > E3 > E4
- B. E3 > E4 > E1 > E2
- C. E4 > E3 > E2 > E1
- D. E2 > E3 > E4 > E1
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Diffraction and interference are closely related phenomena that occur together. Diffraction is the phenomenon of bending of light around the edges of the obstacle, while interference is the combination of waves that results in a new wave pattern. In order to get interference, there must be at least two waves that are diffracting. So while diffraction can occur without interference, interference cannot occur without diffraction. Two slits of width 2 m each in an opaque material are separated by a distance of 6 m. Monochromatic light of wavelength 450 nm is incident normally on the slits. One finds a combined interference and diffraction pattern on the screen.
Q36
mcq
1 mark
The number of peaks of the interference fringes formed within the central peak of the envelope of the diffraction pattern will be :
- A. 2
- B. 3
- C. 4
- D. 6
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Q37
mcq
1 mark
The number of peaks of the interference formed if the slit width is doubled while keeping the distance between the slits same will be :
- A. 1
- B. 2
- C. 3
- D. 4
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Q38
mcq
1 mark
If instead of 450 nm light, another light of wavelength 680 nm is used, number of peaks of the interference formed in the central peak of the envelope of the diffraction pattern will be :
- A. 2
- B. 4
- C. 6
- D. 9
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Q39
mcq
1 mark
Consider the diffraction of light by a single slit described in this case study. The first minimum falls at an angle equal to :
- A. sin-1 (0.12)
- B. sin-1 (0.225)
- C. sin-1 (0.32)
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Q40
mcq
1 mark
(a) Let E1, E2, E3 and E4 be the magnitudes of the electric field between the pairs of plates, I, II, III and IV respectively. Then :
- A. E1 > E2 > E3 > E4
- B. E3 > E4 > E1 > E2
- C. E4 > E3 > E2 > E1
- D. E2 > E3 > E4 > E1
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Q41
mcq
1 mark
(b) An electron is projected from the right plate of set I directly towards its left plate. It just comes to rest at the plate. The speed with which it was projected is about : (Take (e/m) =1.76 1011 C/kg)
- A. 1.3 105 m/s
- B. 2.6 106 m/s
- C. 6.5 105 m/s
- D. 5.2 107 m/s
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Q42
long answer
5 marks
(i) {H$s g_mÝVa n{Å>H$m g§Ym[aÌ, {OgH$s n{Å>H$mAm| Ho$ ~rM H$moB© namd¡ÚwV _mÜ`_ h¡, H$s Ym[aVm Ho$ {bE ì`§OH$ àmßV H$s{OE & (ii) 0·2 m {ÌÁ`m Ho$ {H$gr YmpËdH$ ImoIbo Jmobo H$mo 6 C Amdoe {X`m J`m h¡ & Bg Jmobo Ho$ (i) n¥îR> Am¡a (ii) Ho$ÝÐ na {d^d kmV H$s{OE &
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Q43
long answer
5 marks
(i) Radius R of any thin conductive spherical shell has +Q charge. Using Gauss's theorem, derive the expression for electric field for any point (i) which is inside the shell, and (ii) which is outside the shell. (ii) Show that for same charge density, electric field in case of conductive plate or surface is twice the electric field of any non-conductive sheet.
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Q44
mcq
1 mark
The number of bright fringes formed due to interference on 1 m of screen placed at 3 m away from the slits is :
- A. 2
- B. 3
- C. 6
- D. 10
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Q45
long answer
5 marks
(i) Obtain the expression for the capacitance of a parallel plate capacitor with a dielectric medium between its plates. (ii) A charge of 6 C is given to a hollow metallic sphere of radius 0.2 m. Find the potential at (i) the surface and (ii) the centre of the sphere.
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Q46
long answer
5 marks
(i) A charge + Q is placed on a thin conducting spherical shell of an expression for the electric field at a point lying (i) inside and (ii) outside the shell. (ii) Show that the electric field for same charge density () is twice in case of a conducting plate or surface than in a nonconducting sheet.
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Q47
long answer
5 marks
(i) (1) What is meant by current sensitivity of a galvanometer ? Mention the factors on which it depends. (2) A galvanometer of resistance G is converted into a voltmeter of range (0 V) by using a resistance R. Find the resistance, in terms of R and G, required to convert it into a voltmeter of range 2 V0. (ii) The magnetic flux through a coil of resistance 5 increases with time as : = (2.0 t3 + 5.0 t2 + 6.0 t) mWb. Find the magnitude of induced current through the coil at t = 2 s.
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Q48
long answer
5 marks
(i) A rectangular coil of N turns and area of cross-section A is rotated at a steady angular speed in a uniform magnetic field. Obtain an expression for the emf induced in the coil at any instant of time. (ii) Two coplanar and concentric circular loops L1 and L2 are placed coaxially with their centres coinciding. The radii of L1 and L2 are 1 cm and 100 cm respectively. Calculate the mutual inductance of the loops. (Take 2 = 10)
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Q49
long answer
Trace the path of a ray of light showing refraction through a triangular prism and hence obtain an expression for angle of deviation ( ) in terms of A, i and e, where symbols have their usual meanings. Draw a graph showing the variation of angle of deviation with the angle of incidence.
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Q50
long answer
5 marks
(ii) In the figure, a ray of light is incident on a transparent liquid contained in a thin glass box at an angle of 45 with its one face. The emergent ray passes along the face AB. Find the refractive index of the liquid.
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Q51
long answer
5 marks
(b) (i) The displacement of two light waves, frequency f, emanating from two coherent sources of light, are given by y1 = a cos omega t and y2 = a cos (omega t + phi). phi is the phase difference between the two waves. These light waves superpose at a point. Obtain the expression for the resultant intensity at that point.
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Q52
long answer
5 marks
(ii) find the ratio of intensities at two points on a screen when waves emanating from two slits reaching these points have path differences (i) lambda/6 and (ii) lambda/12.
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