Q1
mcq
1 mark
In a region electric field is given by E = 4 x i N/C. The potential difference between points A (x = 1 m) and B (x = 3 m), (VA – VB) is
- A. –16 V
- B. 16 V
- C. – 8 V
- D. 8 V
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Q2
mcq
1 mark
In an unbiased p-n junction, at equilibrium, which of the following statements is true?
- A. Diffusion current is zero but drift current exists.
- B. Diffusion current exists but drift current is zero.
- C. Diffusion and drift currents are equal and opposite.
- D. Both the diffusion and drift currents exist but are unequal.
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Q3
mcq
1 mark
A copper wire is stretched to increase its length by 1%. Then the change in its resistance is close to
- A. 1%
- B. 4%
- C. –4%
- D. 2%
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Q4
mcq
1 mark
Four independent waves are expressed as: (i) y1 = A1 sin ωt (ii) y2 = A2 sin 2 ωt (iii) y3 = A3 cos ωt (iv) y4 = A4 sin (ωt + π/3). The interference between two of these waves is possible in
- A. (i) and (iii) only
- B. (iii) and (iv) only
- C. (i), (iii) and (iv) only
- D. All of them
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Q5
mcq
1 mark
A concave lens of focal length 40 cm is coaxially in contact with two convex lenses, each of focal length 20 cm, on each side. The focal length of the combination is
- A. zero
- B. 20/3 cm
- C. – 20/3 cm
- D. 40/3 cm
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Q6
mcq
1 mark
The distance-of-closest-approach for an alpha particle is ‘d’ when it moves head-on with speed v towards a target nucleus. If the alpha particle is replaced by a proton moving with the same speed, the new distance-of-closest-approach will be
- A. 2d
- B. d
- C. d/2
- D. d/2
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Q7
mcq
1 mark
Electromagnetic waves used for purification of water are
- A. X-rays
- B. Ultraviolet rays
- C. Infrared rays
- D. Ultrasonic rays
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Q8
mcq
1 mark
A conducting wire connects two charged metallic spheres A and B of radii r1 and r2 respectively. The distance between the spheres is very large compared to their radii. The ratio of electric fields, (EA/EB) at the surfaces of spheres A and B will be
- A. r1/r2
- B. r2/r1
- C. r1^2/r2^2
- D. r2^2/r1^2
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Q9
mcq
1 mark
mbination is
- A. zero
- B. 20/3 cm
- C. – 20/3 cm
- D. 40/3 cm
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Q9
mcq
1 mark
A straight conductor lies along x-axis. It carries a current of 10 A along +x direction. The magnetic field B due to 1 cm segment of this conductor, centred at the origin, at a point (0, 1 m, 0) is
- A. (1 nT) ^j
- B. (10 nT) ^k
- C. – (10 nT) ^k
- D. – (1 nT) ^j
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Q10
mcq
1 mark
The angular width of interference fringes in Young’s double-slit experiment depends on
- A. distance between the slits and the screen only
- B. wavelength of light used only
- C. both wavelength of light used and the slits separation
- D. slits separation only
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Q11
mcq
1 mark
An electromagnetic wave passes from vacuum into a dielectric medium with relative electrical permittivity (3/2) and relative magnetic permeability (8/3). Then, its
- A. wavelength is doubled and frequency remains unchanged.
- B. wavelength is doubled and frequency is halved.
- C. wavelength is halved and frequency remains unchanged.
- D. wavelength and frequency both will remain unchanged.
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Q12
mcq
1 mark
A resistor and an inductor of negligible resistance are connected in series to a 20 V ac source. If the voltage across the resistor is 12 V, the voltage across the inductor will be
- A. 6 V
- B. 8 V
- C. 10 V
- D. 16 V
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Q13
short answer
1 mark
Assertion (A) : In the Bohr-model of a hydrogen atom, energy levels are discrete and quantised. Reason (R) : The electrostatic force on the electron in a hydrogen atom provides the necessary centripetal force due to which it revolves around the nucleus.
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Q14
short answer
1 mark
Assertion (A) : The mass of a nucleus is less than the sum of the masses of its constituent nucleons. Reason (R) : Energy is released when nucleons bind together to form a nucleus.
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Q15
short answer
1 mark
Assertion (A) : All atoms have a net magnetic moment. Reason (R) : Current loop does not behave as a magnetic dipole always.
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Q16
short answer
1 mark
Assertion (A) : If accelerated electrons are passed through a narrow slit, a diffraction pattern is produced. Reason (R) : Electrons behave both as particles and waves.
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Q18
short answer
2 marks
A beam of light consisting of two wavelengths 400 nm and 600 nm is used to illuminate a single slit of width 1 mm. Find the least distance of the point from the central maximum where the dark fringes due to both wavelengths coincide on the screen placed 1.5 m from the slit.
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Q18
short answer
2 marks
Find the ratio of de Broglie wavelength λa associated with an alpha particle to de Broglie wavelength λp associated with a proton if both are moving with the (a) same velocity (b) same kinetic energy.
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Q19
short answer
2 marks
In a Young’s double-slit experimental set-up with slit separation 0.6 mm a beam of light consisting of two wavelengths 440 nm and 660 nm is used to obtain interference pattern on a screen kept 1.5 m in front of the slits. Find the least distance of the point from the central maximum where the bright fringes due to both the wavelengths coincide.
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Q19
short answer
2 marks
What is the order of magnitude of drift velocity of electrons in a conductor? Deduce the relation between the current flowing through a conductor and drift velocity of electrons in it.
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Q20
short answer
2 marks
A wire of length L is bent round into (i) a square coil having N turns and (ii) a circular coil having N turns. The coil in both cases is free to turn about a vertical axis coinciding with the plane of the coil, in a uniform, horizontal magnetic field and carry the same currents. Find the ratio of the maximum value of the torque acting on the square coil to that on the circular coil.
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Q21
short answer
2 marks
Draw a graph showing variation of binding energy per nucleon as a function of mass number A. The binding energy per nucleon for heavy nuclei (A > 170) decreases with increase in mass number. Explain its significance.
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Q22
short answer
2 marks
Find the least distance of the point from the central maximum where the dark fringes due to both wavelengths coincide on the screen placed 1.5 m from the slit.
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Q22
short answer
3 marks
Figure shows a narrow beam of electrons entering with a velocity of 3 x 10^7 m/s, symmetrically through the space between two parallel horizontal plates P1 P1' and P2 P2' kept 2 cm apart. If each plate is 3 cm long, calculate the potential difference V applied between the plates so that the beam just strikes the end P2'.
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Q25
short answer
3 marks
An ac voltage Vi = 12 sin (100 πt) V is applied between points A and B in a network of two ideal diodes and three resistors as shown in figure. During the positive half-cycle of the input voltage Vi supplied to the network. (a) Identify which of the two diodes will conduct and why ? (b) Redraw an equivalent circuit diagram to show...
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Q26
short answer
3 marks
State the two conditions under which total internal reflection occurs.
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Q26
short answer
3 marks
A 12.0 μF capacitor is charged to a potential difference of 150 V. The terminals of the charged capacitor are then connected to those of an uncharged 6.0 μF capacitor. Calculate final potential difference across and charge on, each capacitor.
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Q27
short answer
A transparent container contains layers of three immiscible transparent liquids A, B and C of refractive indices n, 3/4 n and 2/3 n, respectively. A laser beam is incident at the interface between A and B at an angle θ as shown in figure. Prove that the beam does not enter region C at all for sin θ > 2/3.
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Q28
short answer
3 marks
Using Gauss’s law, deduce an expression for electric field at a point due to a uniformly charged infinite plane thin sheet.
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Q28
short answer
3 marks
Draw a labelled ray diagram showing the formation of image by a compound microscope when final image is formed at least distance of distinct vision. Derive an expression for its magnifying power for this case.
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Q29
short answer
Two large thin plane sheets, each having surface charge density σ, are held close and parallel to each other in air. What is the net electric field at a point (i) inside and (ii) outside, the sheets ?
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A researcher performs an experiment on photo-electric effect using two metals A and B with unknown work functions. She illuminates the surfaces of A and B with monochromatic radiation of various frequencies and records the value of corresponding stopping potentials (Vs). The graph shows the variation of stopping potential (Vs) with the frequency of incident radiation (ν) for metals A and B.
Q29
long answer
4 marks
A researcher performs an experiment on photo-electric effect using two metals A and B with unknown work functions. She illuminates the surfaces of A and B with monochromatic radiation of various frequencies and records the value of corresponding stopping potentials (Vs). The graph shows the variation of stopping potential (Vs) with the frequency of incident radiation (ν) for metals A and B.
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Q30
short answer
(a) Obtain the condition of balance of a Wheatstone bridge. (b) Find net resistance of the network of resistors connected between A and B, as shown in figure.
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Q31
long answer
5 marks
(a) State Faraday’s law of electromagnetic induction. (b) Derive an expression for the self-inductance of an air-filled long solenoid of length l and cross-sectional area A having N turns. (c) A conducting rod of length 50 cm, with one end pivoted, is rotated with angular speed of 60 rpm in a uniform magnetic field of 4.0 mT directed perpendicular to the plane of rotation of rod. Find the emf induced in the rod.
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Q32
long answer
(a) Obtain the condition of balance of a Wheatstone bridge.
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Q32
long answer
5 marks
(a) An electric dipole consists of two point charges q and –q separated by a distance 2a. Derive an expression for the electric field E due to this dipole at a point distant r from the centre of the dipole on the equatorial plane. Write the expression for the electric field at a far off point, i.e. r >> a. (b) A dipole is placed in x-y plane such that charges q and –q are located at x = a and x = b respectively. There exists an electric field E = 2 i N C in the region. Calculate the force F and torque τ experienced by the dipole.
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Q33
long answer
(b) Find net resistance of the network of resistors connected between A and B, as shown in figure.
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Q33
long answer
5 marks
(a) Using the relation for refraction at a curved spherical surface, derive the expression for lens maker’s formula. (b) Three lenses L1, L2 and L3, each of focal length 40 cm, are placed coaxially. The distance between L1 and L2 and between L2 and L3 are 120 cm and 20 cm respectively. An object is kept at a distance of 80 cm to the left of lens L1. Find the distance of the final image formed from the object.
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Q34
short answer
An ac voltage Vi = 12 sin (100 πt)V is applied between points A and B in a network of two ideal diodes and three resistors as shown in figure. During the positive half-cycle of the input voltage Vi supplied to the network. (c) Calculate the output voltage drops V0 across the three resistors when the input voltage attains its peak value.
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Q36
short answer
3 marks
A semiconductor has equal electron and hole concentration of 3 × 10^8 m^−3. On doping with a certain impurity, the hole concentration increases to 6 × 10^10 m^−3. (a) What type of semiconductor is obtained on doping ?
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Q37
short answer
A semiconductor has equal electron and hole concentration of 3 × 10^8 m^−3. On doping with a certain impurity, the hole concentration increases to 6 × 10^10 m^−3. (b) Calculate the new electron concentration of the semiconductor.
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Q38
short answer
A semiconductor has equal electron and hole concentration of 3 × 10^8 m^−3. On doping with a certain impurity, the hole concentration increases to 6 × 10^10 m^−3. (c) How does the energy gap of semiconductor change with doping ? Draw the energy band diagram for it.
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Q41
mcq
(I) Graph shows that the work functions of A and B are : (h is Planck constant and e is electronic charge)
- A. ν1 and ν2
- B. V1 and V2
- C. hν1 and hν2
- D. hν1/e and hν2/e
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Q42
mcq
(II) If frequency of incident radiation on A and B is ν > ν2, then the maximum kinetic energy of emitted electrons is -
- A. more for metal A because its work function is less.
- B. more for metal B because its work function is more.
- C. more for metal B because its threshold frequency is more.
- D. same for both A and B because it does not depend on work function of metal.
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Q43
mcq
(III) If the frequency of incident radiation is kept constant but intensity of radiation for both A and B is doubled, then
- A. slope of parallel lines will increase.
- B. slope of parallel lines will decrease.
- C. threshold frequency for both A and B will decrease.
- D. there will be no change in slope of lines but more electrons will be ejected per second.
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Q44
mcq
(I) From the graph, the work functions of A and B are (h is Planck’s constant and e value of charge on an electron)
- A. ν1 and ν2
- B. V1 and V2
- C. hν1 and hν2
- D. hν1/e and hν2/e
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Q45
mcq
(II) For radiation of frequency ν > ν2 incident on the surfaces of A and B, the maximum kinetic energy of ejected electron is
- A. greater for metal A because it has a smaller work function.
- B. greater for metal B because it has a larger work function.
- C. greater for metal B because it has higher threshold frequency.
- D. the same for both metal A and metal B because it is independent of work functions of metals.
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Q46
mcq
(III) If the intensity of the incident radiation for both metals A and B, is doubled keeping its frequency constant, then
- A. the slope of the parallel lines will increase.
- B. the slope of the parallel lines will decrease.
- C. the threshold frequencies for both A and B will decrease.
- D. the slope of the parallel lines will not change but more electrons will be emitted per second.
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Q47
mcq
(IV) The threshold frequency for a metal surface is ν0. If the radiation of frequency 3ν0 illuminates the surface, the maximum kinetic energy (KE) of photoelectrons is E1. If the frequency were increased to 60, the maximum KE of the photoelectrons becomes E2. Then E1/E2 equals
- A. 1/3
- B. 1/2
- C. 2/5
- D. 3/4
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Q48
mcq
Let m be the slope of the graph line for metal B. If e is the value of electron charge, then Planck’s constant ‘h’ is given by
- A. me
- B. 1/me
- C. m/e
- D. e/m
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A galvanometer is used to detect or/and measure small currents in an electrical circuit. It essentially works on the fact that a current-carrying coil experiences a deflecting torque when placed in a magnetic field. This deflection in the coil can be measured and it is related to the current flowing in the coil, the number of turns in the coil, area of the coil and the magnetic field. A hair spring attached to the coil provides a counter torque and helps in measuring the deflection. A galvanometer can be converted to an ammeter or a voltmeter of desired range by using suitable resistances.
Q49
mcq
4 marks
(I) The torque on the coil remains constant irrespective of the coil’s orientation during rotation due to
- A. use of soft iron core which increases the magnetic field.
- B. radial magnetic
- C. null
- D. null
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Q50
mcq
illuminates the surface, the maximum kinetic energy (KE) of photoelectrons is E1. If the frequency were increased to 6ν0, the maximum KE of the photoelectrons becomes E2. Then E1/E2 equals
- A. 1/3
- B. 1/2
- C. 2/5
- D. 3/4
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Q51
mcq
4 marks
The best way to increase current sensitivity of a galvanometer is by
- A. increasing number of turns of the coil
- B. increasing area of coil and magnitic field strength
- C. decreasing area of coil and magnetic field strength
- D. increasing torsional constant of the hair spring
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Q52
mcq
4 marks
A moving coil galvanometer has a coil with area of cross-section 4.0 10–3 m2 and number of turns 50. The coil is rotating in a magnetic field of 0.25 T. The torque acting on the coil when a current of 5 A passes through it is
- A. 1.0 N m
- B. 2.0 N m
- C. 0.50 N m
- D. 0.25 N m
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Q53
mcq
4 marks
A galvanometer with coil of resistance 20 shows full scale deflection for a current of 5 mA. To convert it into an ammeter of range (0 – 10 A), a resistance of
- A. 0.05 should be connected in series with it.
- B. 0.05 should be connected in parallel with it.
- C. 0.01 should be connected in parallel with it.
- D. 0.01 should be connected in series with it.
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Q54
long answer
5 marks
State Faraday’s law of electromagnetic induction.
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Q55
long answer
5 marks
Derive an expression for the self-inductance of an air-filled long solenoid of length l and cross-sectional area A having N turns.
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Q56
long answer
5 marks
A conducting rod of length 50 cm, with one end pivoted, is rotated with angular speed of 60 rpm in a uniform magnetic field of 4.0 mT directed perpendicular
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Q58
long answer
5 marks
(a) Draw a labelled diagram of a step-up transformer. State the principle on which it works and obtain the ratio of secondary voltage to primary voltage in terms of number of turns and currents in the two coils. (b) The ratio of the number of turns in the primary to the secondary of an ideal transformer is 1 : 5. If 5 kW power at 200 V is supplied to the primary, find (i) current in the primary, and (ii) output voltage.
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Q60
long answer
5 marks
(a) Two cells of emf E1 and E2 with internal resistances r1 and r2 respectively, are connected in parallel by connecting their positive terminals together and negative terminals together. Deduce an expression for equivalent emf and equivalent internal resistance of the combination. (b) A parallel combination, as stated in (a) above, of two cells of emfs E and 3E and internal resistances R each is connected across a resistance 2R. Find the current that flows through resistance 2R.
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Q62
long answer
(a) Draw a ray diagram to show the image formation by a concave mirror when the object is placed between its focus and centre of curvature. Using this diagram, derive the mirror formula. (b) A concave mirror produces a two times magnified virtual image of an object kept at a distance of 10 cm in front of it. Find the focal length of this mirror.
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