Q1
mcq
1 mark
A charge on the axis of a short electric dipole at a distance r experiences a force F. If the distance of the charge is doubled, the force on the charge will be :
- A. 16F
- B. 8F
- C. 4F
- D. 2F
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Q2
mcq
1 mark
For a metallic conductor, the correct representation of variation of resistance R with temperature T is :
- A. Graph representation a
- B. Graph representation b
- C. Graph representation c
- D. Graph representation d
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Q3
mcq
1 mark
The potential difference across a cell in an open circuit is 8 V. It falls to 4 V when a current of 4 A is drawn from it. The internal resistance of the cell is :
- A. 4
- B. 3
- C. 2
- D. 1
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Q4
mcq
1 mark
A steady current flows through a metallic wire whose area of cross-section (A) increases continuously from one end of the wire to the other. The magnitude of drift velocity (vd) of the free electrons as a function of the cross-sectional area (A) can be represented by :
- A. Graph representation a
- B. Graph representation b
- C. Graph representation c
- D. Graph representation d
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Q5
mcq
1 mark
A diamagnetic substance is brought near a pole of a bar magnet. This substance will be :
- A. Repelled by both the poles.
- B. Attracted by both the poles.
- C. Repelled by the north pole and attracted by the south pole.
- D. Attracted by the north pole and repelled by the south pole.
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Q5
mcq
A diamagnetic substance is brought near the north or south pole of a bar magnet. It will be :
- A. repelled by both the poles.
- B. attracted by both the poles.
- C. repelled by the north pole and attracted by the south pole.
- D. attracted by the north pole and repelled by the south pole.
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Q6
mcq
A circular coil of radius 8.0 cm and 40 turns is rotated about its vertical diameter with an angular speed of 25 rad s^-1 in a uniform horizontal magnetic field of magnitude 3.0 x 10^-2 T. The maximum emf induced in the coil is :
- A. 0.12 V
- B. 0.15 V
- C. 0.19 V
- D. 0.22 V
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Q7
mcq
Figure shows a rectangular conductor PSRQ in which movable arm PQ of emf induced when PQ is moved with a velocity v does not depend on :
- A. magnetic field ( B )
- B. velocity ( v )
- C. resistance (r)
- D. length of PQ
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Q8
mcq
In the process of charging of a capacitor, the current produced between the plates of the capacitor is :
- A. epsilon0 (dE/dt)
- B. (1/epsilon0) (dE/dt)
- C. epsilon0 (dE/dt)
- D. (1/epsilon0) (dE/dt)
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Q9
mcq
For a concave mirror of focal length f, the minimum distance between the object and its real image is :
- A. zero
- B. f
- C. 2f
- D. 4f
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Q10
mcq
The radius of the nth orbit in Bohr model of hydrogen atom is proportional to :
- A. 1/n^2
- B. 1/n
- C. n^2
- D. n
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Q11
mcq
Hydrogen atom initially in the ground state, absorbs a photon which excites it to n = 5 level. The wavelength of the photon is :
- A. 975 nm
- B. 740 nm
- C. 523 nm
- D. 95 nm
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Q12
mcq
The mass density of a nucleus of mass number A is :
- A. proportional to A^(1/3)
- B. proportional to A^(2/3)
- C. proportional to A^3
- D. independent of A
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Q13
mcq
An ac source of voltage is connected in series with a p-n junction diode and a load resistor. The correct option for output voltage across load resistance will be :
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Q14
mcq
When an intrinsic semiconductor is doped with a small amount of trivalent impurity, then :
- A. its resistance increases.
- B. it becomes a p-type semiconductor.
- C. there will be more free electrons than holes in the semiconductor.
- D. dopant atoms become donor atoms.
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Q15
mcq
In the energy-band diagram of n-type Si, the gap between the bottom of the conduction band EC and the donor energy level ED is of the order of :
- A. 10 eV
- B. 1 eV
- C. 0.1 eV
- D. 0.01 eV
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Q16
short answer
Assertion (A) : When a bar of copper is placed in an external magnetic field, the field lines get concentrated inside the bar. Reason (R) : Copper is a paramagnetic substance.
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Q17
short answer
Assertion (A) : The phase difference between any two points on a wavefront is zero. Reason (R) : All points on a wavefront are at the same distance from the source and thus oscillate in the same phase.
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Q18
short answer
Assertion (A) : Photoelectric effect demonstrates the particle nature of light. Reason (R) : Photoelectric current is proportional to intensity of incident radiation for frequencies more than the threshold frequency.
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Q19
long answer
2 marks
An alpha particle is projected with velocity v = (3·0 105 m/s) i into a region in which magnetic field B = [(0·4 T) i +(0·3T) j ] exists. Calculate the acceleration of the particle in the region. i , j and k are unit vectors along x, y and z axis respectively and charge to mass ratio for alpha particle is 4·8 107 C/kg.
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Q20
short answer
2 marks
Consider an induced magnetic field due to changing electric field and an induced electric field due to changing magnetic field. Which one is more easily observed ? Justify your answer.
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Q21
long answer
2 marks
(a) Draw a ray diagram showing the propagation of a plane wave refracting at a plane surface separating two media. (b) Why is a reflecting telescope preferred over a refracting telescope ? Justify your answer giving two reasons.
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Q22
short answer
2 marks
Two coherent monochromatic light beams of intensities I and 4I superpose each other. Find the ratio of maximum and minimum intensities in the resulting beam.
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Q23
short answer
2 marks
The ground state energy of hydrogen atom is 13 6 eV. What is the potential energy and kinetic energy of an electron in the third excited state ?
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Q24
long answer
2 marks
(a) Differentiate between intrinsic and extrinsic semiconductors. OR (b) Draw the circuit arrangement for studying the V I characteristics of a p-n junction diode in forward bias and reverse bias. Show the plot of V I characteristic of a silicon diode.
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Q25
short answer
2 marks
Briefly explain how the diffusion and drift currents contribute to the formation of potential barrier in a p-n junction diode.
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Q26
long answer
3 marks
(a) Twelve negative charges of same magnitude are equally spaced and fixed on the circumference of a circle of radius R as shown in Fig. (i). Relative to potential being zero at infinity, find the electric potential and electric field at the centre C of the circle. (b) If the charges are unequally spaced and fixed on an arc of 120 of radius R as shown in Fig. (ii), find electric potential at the centre C.
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Q27
long answer
3 marks
(a) How does the resistance differ from impedance ? With the help of a suitable phasor diagram, obtain an expression for impedance of a series LCR circuit, connected to a source v = vm sin t.
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Q27
long answer
3 marks
(b) Find the condition for resonance in a series LCR circuit connected to a source v = vm sin t, where can be varied. Give the factors on which the resonant frequency of a series LCR circuit depends. Plot a graph showing the variation of electric current with frequency in a series LCR circuit.
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Q28
long answer
28. A long solenoid of radius r consists of n turns per unit length. A current I = I0 sin t flows in the solenoid. A coil of N turns is wound tightly around it near its centre. What is : (a) the induced emf in the coil ? (b) the mutual inductance between the solenoid and the coil ?
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Q29
long answer
29. How does Einstein explain the photoelectric emission from a metal surface ? Explain briefly. Plot the variation of photocurrent with : (a) collector plate potential for different intensity of incident radiation, and (b) intensity of incident radiation.
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Q30
long answer
3 marks
30. (a) Draw the energy level diagram for hydrogen atom. Mark the transitions corresponding to the series lying in the ultraviolet region, visible region and infrared region.
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Q30
long answer
3 marks
(b) Draw a diagram to show the variation of binding energy per nucleon with mass number for different nuclei and mention its two features. Why do lighter nuclei usually undergo nuclear fusion ?
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Q31
long answer
5 marks
31. (a) (i) State Coulomb's law in electrostatics and write it in vector form, for two charges. (ii) Gauss's law is based on the inverse square dependence on distance. Explain. (iii) Two charges A (charge q) and B (charge 2q) are located at points (0, 0) and (a, a) respectively. Let ^i and ^j be the unit vectors along x-axis and y-axis respectively. Find the force exerted by A on B, in terms of ^i and ^j.
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Q31
long answer
5 marks
(b) (i) Derive an expression for the electric field at a point on the equatorial plane of an electric dipole consisting of charges q and q separated by a distance 2a. (ii) The distance of a far off point on the equatorial plane of an electric dipole is halved. How will the electric field be affected for the dipole ? (iii) Two identical electric dipoles are placed along the diagonals of a square ABCD of side 2 m as shown in the figure. Obtain the magnitude and direction of the net electric field at the centre (O) of the square.
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Q36
short answer
Derive an expression for electric field in vector form, for two charges.
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Q37
short answer
Explain inverse-square dependence on distance for two charges.
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Q38
short answer
5 marks
Two charges A (charge q) and B (charge 2q) are located at points (0, 0) and (a, a) respectively. Let i-hat and j-hat be the unit vectors along x-axis and y-axis respectively. Find the force exerted by A on B, in terms of i-hat and j-hat.
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Q39
long answer
Derive an expression for the electric field at a point on the equatorial plane of an electric dipole consisting of charges +q and -q separated by a distance 2a.
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Q40
short answer
The distance of a far off point on the equatorial plane of an electric dipole is halved. How will the electric field be affected for the dipole?
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Q41
long answer
5 marks
Two identical electric dipoles are placed along the diagonals of a square ABCD of side 2 m as shown in the figure. Obtain the magnitude and direction of the net electric field at the centre (O) of the square.
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Q42
long answer
State Biot-Savart law for the magnetic field due to a current carrying element. Use this law to obtain an expression for the magnetic field at the centre of a circular current loop, indicating the direction of magnetic field.
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Q43
short answer
5 marks
An electron is revolving around the nucleus in a circular orbit with a speed of 10^7 m/s. If the radius of the orbit is 10^-10 m, find the current constituted by the revolving electron in the orbit.
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Q44
long answer
Derive an expression for the force acting on a current carrying straight conductor kept in a magnetic field. State the rule which is used to find the direction of this force. Give the condition under which this force is (1) maximum, and (2) minimum.
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Q45
short answer
5 marks
Two long parallel straight wires A and B are 2.5 cm apart in air. They carry 5.0 A and 2.5 A currents respectively in opposite directions. Calculate the magnitude of the force exerted by wire A on a 10 cm length of wire B.
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Q46
short answer
(1) Write two points of difference between an interference pattern and a diffraction pattern. (2) Name any two factors on which the fringe width in a Young's double-slit experiment depends.
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Q47
short answer
5 marks
In a Young's double-slit experiment, the two slits are separated by a distance equal to 100 times the wavelength of light that passes through the slits. Calculate: (1) the angular separation in radians between the central maximum and the adjacent maximum. (2) the distance between these two maxima on a screen 50 cm from the slits.
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Q48
long answer
A spherical surface of radius of curvature R separates two media of refractive indices n1 and n2. A point object is placed in front of the surface at distance u in medium of refractive index n1 and its image is formed by the surface at distance v, in the medium of refractive index n2. Derive a relation between u and v.
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Q49
short answer
5 marks
A solid glass sphere of radius 6.0 cm has a small air bubble trapped at a distance 3.0 cm from its centre C as shown in the figure. The refractive index of the material of the sphere is 1.5. Find the apparent position of this bubble when seen through the surface of the sphere from an outside point E in air.
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The following figure shows a circuit diagram. We can find the currents through and potential differences across different resistors using Kirchhoff
Q50
short answer
1 mark
Which points are at the same potential in the circuit ?
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Q51
short answer
1 mark
What is the current through arm bg ?
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Q52
short answer
2 marks
Find the potential difference across resistance R3.
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Q53
short answer
2 marks
What is the power dissipated in resistance R2 ?
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Strontium titanate is a rare oxide a natural mineral found in Siberia. It is used as a substitute for diamond because its refractive index and critical angle are 2 41 and 24 5 , respectively, which are approximately equal to the refractive index and critical angle of diamond. It has all the properties of diamond. Even an expert jeweller is unable to differentiate between diamond and strontium titanate. A ray of light is incident normally on one face of an equilateral triangular prism ABC made of strontium titanate.
Q54
short answer
1 mark
Trace the path of the ray showing its passage through the prism.
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Q55
short answer
1 mark
Find the velocity of light through the prism.
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Q56
short answer
2 marks
Briefly explain two applications of total internal reflection.
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Q57
short answer
2 marks
Define total internal reflection of light. Give two conditions for it.
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