Q1
mcq
1 mark
Two identical circular coaxial coils A and B, arranged in vertical planes parallel to each other, carry currents in the same direction. If the distance between the coils is decreased at a constant rate, the current :
- A. increases in A and decreases in B.
- B. decreases in both A and B.
- C. increases in both A and B.
- D. remains same in both A and B.
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Q2
mcq
1 mark
In the process of charging of a capacitor, the current produced between the plates of the capacitor is :
- A. 0 dt d E
- B. 0 1 dt d E
- C. 0 dt d E
- D. 0 1 dt d E where symbols have their usual meanings.
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Q3
mcq
The minimum distance between an object and its real image formed by a convex lens of focal length f is :
- A. f
- B. 2f
- C. 3f
- D. 4f
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Q4
mcq
A photon of energy 7 eV is incident on a metal surface having the work function of 3 75 eV. The stopping potential is :
- A. 1 75 eV
- B. 2 45 eV
- C. 3 25 eV
- D. 3 75 eV
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Q5
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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Q6
mcq
The atomic number of an atom represents :
- A. number of neutrons in nucleus.
- B. total number of protons and electrons in the atom.
- C. number of protons in nucleus.
- D. total number of protons and neutrons in nucleus.
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Q8
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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Q9
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 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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Q10
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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Q11
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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Q13
mcq
Copper ke do belnatmak taron ke dravyamano ka anupat 1 : 3 tatha unki lambaiyon ka anupat 5 : 3 hai. In taron ke pratirodhon ka anupat hoga :
- A. 1 : 3
- B. 2 : 5
- C. 2 : 3
- D. 3 : 5
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Q13
mcq
The masses of two cylindrical wires of copper are in the ratio of 1 : 3 and their lengths are in the ratio of 5 : 3. The ratio of their resistances will be :
- A. 1 : 3
- B. 2 : 5
- C. 2 : 3
- D. 3 : 5
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Q14
mcq
Which one of the following is the correct representation of variation of conductivity of a conductor with temperature ?
- A. (a)
- B. (b)
- C. (c)
- D. (d)
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Q16
mcq
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.
- 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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Q17
mcq
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.
- 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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Q18
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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Q19
short answer
2 marks
Explain briefly how diffusion and drift currents contribute to the formation of the barrier potential in a p-n junction diode.
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Q19
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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Q20
short answer
2 marks
(a) Distinguish 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 V-I characteristic graph for a silicon diode.
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Q21
short answer
2 marks
An alpha particle is projected with a velocity v = (3.0 * 10^5 m/s) i^ into a region where a magnetic field B = [(0.4 T) i^ + (0.3 T) j^] exists. Calculate the acceleration of the particle in this region. (i^, j^ and k^ are unit vectors along x, y and z axes respectively and the charge to mass ratio for an alpha particle is 4.8 * 10^7 C/kg).
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Q22
short answer
2 marks
A plane electromagnetic wave is propagating in vacuum along x-axis. (a) Mention the directions of electric field vector and magnetic field vector. (b) The magnitudes of the electric and magnetic fields of a plane electromagnetic wave are E0 and B0 respectively. Find the ratio of the energy densities of the electric field and the magnetic field.
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Q22
short answer
2 marks
A plane electromagnetic wave propagates in vacuum along x-axis. (a) Give the direction of electric field and magnetic field vectors. (b) E0 and B0 are the magnitudes of electric and magnetic fields respectively in a plane electromagnetic wave. Find the ratio of energy densities of electric field and magnetic field.
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Q23
short answer
2 marks
(a) Draw a ray diagram to show the propagation of a plane wave refracting at a plane surface separating two media. Also verify Snell's law of refraction. OR (b) Why is a reflecting telescope preferred over a refracting telescope ? Justify your answer giving two reasons.
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Q24
short answer
2 marks
A double-convex lens of power 4 D is manufactured from a glass of refractive index 1·5. What is the radius of curvature of each face of this lens if both faces have the same radius of curvature ?
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Q25
short answer
2 marks
Calculate the wavelength of the second line of Lyman series in a spectrum of hydrogen atom. (Take Rydberg constant, R = 1·1 107 m-1).
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Q26
long answer
3 marks
(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. OR (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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Q26
long answer
3 marks
(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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Q26
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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Q27
long answer
3 marks
The threshold wavelength for a metal is 3315 Å. What should be the wavelength of light incident on the metal surface so that the maximum kinetic energy of the emitted photoelectrons be 1·25 eV ?
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Q28
short answer
2 marks
What is the radius of curvature of each face of this lens if both faces have the same radius of curvature ?
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Q28
long answer
3 marks
The primary and the secondary coils of an ideal step-down transformer consist of 650 and 25 turns respectively. When the primary coil of this transformer is connected to 240 V mains, the current in the primary coil is 1.5 A. Calculate : (a) the voltage across the secondary coil (b) the current in the secondary coil (c) the average power delivered to the output circuit
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Q29
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. OR (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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Q30
short answer
3 marks
A 100 F capacitor is charged by a 12 V battery. (a) How much electrostatic energy is stored by the capacitor ? (b) The capacitor is disconnected from the battery and connected in parallel to another uncharged 100 F capacitor. What is the electrostatic energy stored by the system ?
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Q31
long answer
5 marks
(a) (i) State Biot-Savart law for 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 loop, carrying current. Draw magnetic field lines for a current loop indicating the direction of magnetic field. (ii) An electron is revolving around the nucleus in a circular orbit with a speed of 10^7 m s^-1. 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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Q35
long answer
5 marks
State Biot-Savart law for 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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Q36
long 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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Q37
long answer
5 marks
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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Q38
long answer
5 marks
Two long parallel straight wires A and B are 25 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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Q39
short answer
5 marks
Write two points of difference between an interference pattern and a diffraction pattern.
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Q40
short answer
5 marks
Name any two factors on which the fringe width in a Young's double-slit experiment depends.
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Q41
long answer
5 marks
In 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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Q42
long answer
5 marks
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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Q43
long 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. 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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Q44
short answer
5 marks
State Coulomb's law in electrostatics and write it in vector form, for two charges.
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Q45
short answer
5 marks
Explain why Gauss's law is based on inverse-square dependence on distance.
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Q46
long answer
5 marks
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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Q47
long answer
5 marks
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 distance 2a.
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Q48
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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Q49
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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The following figure shows a circuit diagram. We can find the currents through and potential differences across different resistors using Kirchhoff Answer the following questions based on the above :
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. Answer the following questions based on the above :
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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