Q1
mcq
1 mark
A voltage signal is described by : v = V0 for 0 ≤ t < T/2, = 0 for T/2 ≤ t < T for a cycle. Its rms value is :
- A. V0/2
- B. V0
- C. V0/√2
- D. 2 V0
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Q2
mcq
1 mark
The ratio of maximum frequency and minimum frequency of light
- A. 9/11
- B. 5/9
- C. 7/11
- D. 7/16
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Q3
mcq
1 mark
At a certain temperature in an intrinsic semiconductor, the electrons and holes concentration is 1·5 1016 m 3. When it is doped with a trivalent dopant, hole concentration increases to 4·5 1022 m3. In the doped semiconductor, the concentration of electrons (ne) will be :
- A. 3 106 m 3
- B. 5 107 m 3
- C. 5 109 m 3
- D. 6·75 1038 m 3
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Q4
mcq
An infinitely long uniformly charged wire produces an electric field of 18 * 10^4 NC^-1 at a distance of 1.0 cm. The linear charge density on the wire is :
- A. 1.12 * 10^-14 Cm^-1
- B. 3.08 * 10^-15 Cm^-1
- C. 1.0 * 10^-9 Cm^-1
- D. 1.0 * 10^-7 Cm^-1
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Q5
mcq
At 0 K, the resistivity of an intrinsic semiconductor is :
- A. same as that at 0 C
- B. same as that at 300 K
- C. zero
- D. infinite
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Q6
mcq
Light of frequency 6.4 * 10^14 Hz is incident on a metal of work function 2.14 eV. The maximum kinetic energy of the emitted electrons is about :
- A. 0.25 eV
- B. 0.51 eV
- C. 1.02 eV
- D. 0.10 eV
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Q7
mcq
In an experiment on photoelectric effect, the intensity of incident radiation is increased, keeping the frequency v the same. The number of photoelectrons emitted will :
- A. increase
- B. decrease
- C. remain same
- D. depend on frequency
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Q8
mcq
The SI unit of mobility of charge carriers is :
- A. s^-1
- B. m^2 V^-1 s^-1
- C. m s^-1 V^-1
- D. m
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Q9
mcq
An inductor, a capacitor and a resistor are connected in series across an ac source of voltage. If the frequency of the source is decreased gradually, the reactance of :
- A. both the inductor and the capacitor decreases.
- B. inductor decreases and the capacitor increases.
- C. both the inductor and the capacitor increases.
- D. inductor increases and the capacitor decreases.
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Q10
mcq
In a moving coil galvanometer, the deflecting torque acting on the coil is related to the current I flowing through it as :
- A. I^3
- B. I^2
- C. I
- D. I
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Q11
mcq
In the wave picture of light, the intensity I of light is related to the amplitude A of the wave as :
- A. I proportional to A
- B. I proportional to A
- C. I proportional to A^2
- D. I proportional to 2A
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Q12
mcq
Electromagnetic waves of wavelength of the order of a few meters were first produced and detected in the laboratory by :
- A. J.C. Maxwell
- B. J.C. Bose
- C. H.R. Hertz
- D. G. Marconi
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Q13
mcq
The emf and internal resistance of a cell are E and r respectively. It is connected across an external resistance R = 2r. The potential drop across the terminals of the cell will be :
- A. E/4
- B. E/2
- C. 2E/3
- D. 3E/4
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Q14
mcq
In a single-slit diffraction experiment, the width of the slit is halved. The width of the central maximum, in the diffraction pattern, will become :
- A. half
- B. twice
- C. four times
- D. one-fourth
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Q15
mcq
Which of the following graphs correctly represents the variation of the magnitude of the magnetic field outside a straight infinite current the wire ?
- A. (a)
- B. (b)
- C. (c)
- D. (d)
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Q16
short answer
Assertion (A) : When radius of a circular loop carrying a steady current is doubled, its magnetic moment becomes four times. Reason (R): The magnetic moment of a circular loop carrying a steady current is proportional to the area of the loop.
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Q17
short answer
Assertion (A): The nucleus X 7/3 is more stable than the nucleus Y 4/3. Reason (R): X 7/3 contains more number of protons.
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Q18
short answer
Assertion (A) : The internal resistance of a cell is constant. Reason (R) : Ionic concentration of the electrolyte remains same during use of a cell.
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Q19
short answer
2 marks
How is the width of depletion layer of a p-n junction diode affected when it is (i) forward biased, and (ii) reverse biased ? Justify your answers.
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Q20
short answer
2 marks
Explain the property of a p-n junction which makes it suitable for rectifying alternating voltages. Differentiate between a half-wave and a full-wave rectifier.
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Q21
short answer
2 marks
(a) Draw a graph showing the 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 the increase in mass number. Explain.
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Q23
short answer
2 marks
Two wires of equal lengths are shaped in the form of a square loop and a circular loop. Both loops are suspended in a uniform magnetic field. Prove that for the same current, the circular loop will experience larger torque.
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Q23
short answer
2 marks
(a) State Huygens principle. How did Huygens explain the absence of the backwave?
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Q24
short answer
2 marks
(b) Show the reflection/refraction of a plane wave by (i) concave mirror, and (ii) a convex lens.
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Q25
short answer
2 marks
The refractive indices of two media A and B are 2 and 2 respectively. What is the critical angle for their interface?
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Q26
short answer
3 marks
(a) A particle of mass m and charge q is accelerated through a potential difference V. Plot a graph of de Broglie wavelength associated with it as a function of V.
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Q27
short answer
3 marks
(b) Calculate the energy acquired by and de Broglie wavelength associated with, an electron accelerated through a potential difference of 400 V.
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Q28
short answer
3 marks
(a) An ac source v = vm sin wt is connected across an ideal capacitor. Derive the expression for the (i) current flowing in the circuit, and (ii) reactance of the capacitor. Plot a graph of current i versus t.
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Q29
short answer
3 marks
(b) A series combination of an inductor L, a capacitor C and a resistor R is connected across an ac source of voltage in a circuit. Obtain an expression for the average power consumed by the circuit. Find power factor for (i) purely inductive circuit, and (ii) purely resistive circuit.
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Q29
short answer
A rectangular loop of sides 25 cm and 20 cm is lying in x-y plane. It is subjected to a magnetic field B = (5t2 + 2t + 10) k, where B is in Tesla and t is in seconds. If the resistance of the loop is 4, find the emf induced and the induced current in the loop at t = 5 s.
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Q30
short answer
3 marks
(a) (i) Prove that the nuclear density is same for all nuclei. (ii) Draw a plot of potential energy of a pair of nucleons as a function of their separation. Draw two inferences from this plot.
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Q30
short answer
3 marks
V and R can be varied. If the current that flows in the circuit is I, draw a plot showing the variation of power consumed by the resistor as a function of : (a) R, keeping V constant (b) I, keeping R constant (c) V, keeping R constant
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Q31
short answer
3 marks
(b) (i) Draw a graph to show the variation of the number of scattered particles detected (N) in Geiger-Marsden experiment as a function of scattering angle (theta). (ii) Discuss briefly two conclusions that can be drawn from this graph and how they lead to the discovery of nucleus in an atom.
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Q34
long answer
5 marks
(i) Write the principle and explain the working of a moving coil galvanometer. A galvanometer as such cannot be used to measure the current in a circuit. Why ? (ii) Why is the magnetic field made radial in a moving coil galvanometer ? How is it achieved ?
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Q35
long answer
5 marks
(i) Derive an expression for magnetic field on the axis of a current carrying circular loop. (ii) Write any two points of difference between a diamagnetic and a paramagnetic substance.
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Q36
long answer
5 marks
(i) Draw a ray diagram showing refraction of a ray of light through a triangular glass prism. Hence, obtain the relation for the refractive index in terms of angle of prism (A) and angle of minimum deviation (m). (ii) The radii of curvature of the two surfaces of a concave lens are 20 cm each. Find the refractive index of the material of the lens if its power is 5.0 D.
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Q37
long answer
5 marks
(i) Define electric flux and write its SI unit. (ii) Use Gauss's law to derive an expression for electric field due to a uniformly charged infinite plane sheet. (iii) A cube of side L is kept in space, as shown in the figure. An electric field E = (Ax + B) i exists in the region. Find the net charge enclosed by the cube.
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Q38
long answer
(a) (i) Draw a ray diagram showing the formation of a real image of, obtain the relation for the
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Q39
long answer
5 marks
(ii) A 1.8 m tall person stands in front of a convex lens of focal length 1 m, at a distance of 5 m. Find the position and height of the image formed.
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Q40
long answer
(b) (i) Draw a ray diagram showing refraction of a ray of light through a triangular glass prism. Hence, obtain the relation for the refractive index in terms of angle of prism (A) and angle of minimum deviation (m).
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Q41
long answer
5 marks
(ii) The radii of curvature of the two surfaces of a concave lens are 20 cm each. Find the refractive index of the material of the lens if its power is 5.0 D.
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Q42
long answer
(a) (i) Define electric flux and write its SI unit.
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Q43
long answer
(ii) [Derive expression] due to a uniformly charged infinite plane sheet.
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Q44
long answer
5 marks
(iii) A cube of side L is kept in space, as shown in the figure. An electric field E = (Ax + B) i exists in the region. Find the net charge enclosed by the cube.
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Diffraction of light is bending of light around the corners of an object whose size is comparable with the wavelength of light. Diffraction actually defines the limits of ray optics. This limit for optical instruments is set by the wavelength of light. An experimental arrangement is set up to observe the diffraction pattern due to a single slit.
Q45
short answer
1 mark
(a) How will the width of central maximum be affected if the wavelength of light is increased?
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Q46
short answer
1 mark
(b) Under what condition is the first minimum obtained?
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Q47
short answer
2 marks
(c) Write two points of difference between interference and diffraction patterns.
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Q48
short answer
2 marks
(c) Two students are separated by a 7 m partition wall in a room 10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see each other even though they can converse easily?
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A beam of electrons moving horizontally with a velocity of 3 107 m/s enters a region between two plates as shown in the figure. A suitable potential difference is applied across the plates such that the electron beam just strikes the edge of the lower plate.
Q49
short answer
1 mark
(a) How long does an electron take to strike the edge?
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Q50
short answer
1 mark
(b) What is the shape of the path followed by the electron and why?
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Q51
short answer
2 marks
(c) Find the potential difference applied.
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Q52
short answer
2 marks
(c) Find the magnitude and direction of the magnetic field which should be created in the space between the plates so that the electron beam goes straight undeviated.
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