Electric Charges and Fields
Dec-2024
The presence of dielectric medium _______ (increases/decreases) the force between two point charges. [1, 2]
A polythene piece rubbed with wool is found to have a negative charge of 3 × 10⁻⁷ C. Estimate the number of electrons transferred. [1, 2]
(a) An electric dipole is placed in a uniform electric field E, the electrostatic potential energy of the dipole system is _______.) [3, 4]
Dec-2023
Gauss’s law in Electrostatics is applicable for (all surfaces/only closed surfaces) [5, 6]
Answer any 6 questions from 15 to 21. Each carries 3 scores.
Explain the behaviour of electric field outside, surface and inside of a charged shell. [7, 8]
Dec-2022
The S.I. unit of charge is _______. [9, 10]
Write any two properties of electric charge. [9, 10]
Define electric dipole moment. Give its direction. [9, 10]
Find an expression for electric field intensity due to electric dipole on its equatorial line, Draw a neat diagram of the case. [11, 12]
Electric field lines are used for representing electric field.
(a) List two important properties of electric field lines.
(b) Draw electric field line representing
(i) uniform electric field.
(ii) electric field of an electric dipole. [11, 12]
Gauss’s theorem connects the electric flux and the electric charge that produces the flux.
(a) State Gauss’s theorem and write an equation showing it.
(b) With a diagram, derive the equation for the electric field due to a charged conducting wire. [13, 14]
Electrostatic Potential and Capacitance
Dec-2024
(b) An electron and a proton are separated by a distance of 1 Fermi. Calculate the electrostatic potential energy of the system. (Charge of electron/proton = ± 1.6 × 10⁻¹⁹ C) [3, 4]
Dec-2023
Two capacitors of capacitances 2 µF and 4 µF are connected in series. What is its effective capacitance? [15, 16]
What is dielectric polarisation? Explain it with polar and non-polar molecules, give examples. [8, 16]
Dec-2022
Work done in moving a charge of +3 C on an equipotential surface of 6 V is _______.
(a) 3 J
(b) 6 J
(c) 18 J
(d) 0 J [9, 10]
Two charges of +2 µC and −5 µC are kept 2 cm apart in air. Find the electric potential at the midpoint of the line joining the charges. [11, 12]
A capacitor marked 10 µF, 25 V is charged by connecting it to a voltage of 10 V. Find the energy stored in the capacitor. Where do capacitors store energy? [11, 12]
If two copper plates, each of area ‘A’ are kept parallel at a distance ‘d’ apart in air, it’s a parallel plate capacitor.
(a) Define capacitance of this arrangement.
(b) Derive a formula for the capacitance of this capacitor.
(c) How capacitance changes if the distance between the plates doubled? [11, 12]
Electric potential is used for explaining strength of electric field.
(a) Define electric potential at a point in an electric field.
(b) Obtain the potential due to an electric dipole at a distance ‘r’ away from its center.
(c) How is electric field intensity related to electric potential? [13, 14]
Current Electricity
Dec-2024
(a) Three cells having emf’s E₁, E₂ and E₃ having internal resistance r₁, r₂ and r₃ are connected as shown below: [Diagram] Write the effective emf and effective internal resistance of the combination.
(b) [Circuit Diagram provided with resistors and cells]
(i) Apply junction rule at ‘a’.
(ii) Apply loop rule at loop abdha. [17, 18]
Dec-2023
Define mobility, give its SI unit. [15, 16]
Dec-2022
Resistance of a conductor _______ with temperature.
(a) does not change
(b) increases
(c) decreases [9, 10]
State Kirchhoff’s junction rule. [9, 10]
Define drift velocity. Derive the expression connecting drift velocity and current. [11, 12]
Four resistors connected in a particular way makes, Wheatstone’s bridge.
(a) Show Wheatstone’s bridge of resistors in a figure.
(b) Write Kirchhoff’s loop rule, in two equations, as used in this bridge.
(c) Arrive at the balancing condition of the bridge in terms of resistors. [13, 14]
Moving Charges and Magnetism
Dec-2024
Write any two differences between electric field and magnetic field. [1, 2]
(a) Write the mathematical form of Ampere’s circuital theorem.
(b) Using Biot–Savart law, derive an equation to find the magnetic field at an axial point of a current carrying circular loop. [19, 20]
Dec-2023
Magnetic field at the centre of a current carrying solenoid along its axis is
(a) B = 0
(b) B = (1/2)µ₀ni
(c) B = µ₀ni
(d) B = 2µ₀ni [5, 6]
Two current carrying conductors are arranged as shown in figure: [Diagram of parallel conductors]
(a) Derive the expression for force per unit length of the conductor.
(b) Define SI unit of current. [21, 22]
Dec-2022
Work done by magnetic Lorentz force on a moving charge in a magnetic field is always _______.
(a) +ve
(b) −ve
(c) zero [9, 10]
How do you convert a galvanometer into an ammeter? Explain. [9, 10]
A circular coil of wire consisting of 100 turns, each of radius 8.0 cm carries a current of 0.40 A. What is the magnitude of the magnetic field at the centre of the coil? [11, 12]
Biot Savart’s law gives the magnetic field produced by electric current.
(a) State Biot-Savart’s law. Explain the symbols used.
(b) Using Biot-Savart’s law, find the magnetic field due to a circular coil with current on its axial line. [13, 14]
Magnetism and Matter
Dec-2024
The susceptibility of a magnetic material is 5499, its relative permeability is _______. [1, 2]
State Gauss’s law in magnetism. [3, 4]
Write any two properties of dia, para and ferromagnetic substances. [3, 4]
Dec-2023
Which one of the following figures represents correct magnetic field? [Figures (a) and (b) showing field lines] [5, 6]
Explain the torque on a magnetic dipole placed in a uniform magnetic field. [15, 16]
Compare dia, para and ferromagnetic substances with suitable examples. [8, 16]
Dec-2022
The net magnetic flux through any closed surface is zero. This law is called _______. [9, 10]
List any three properties of dia, para and ferro magnetic materials. [11, 12]
Electromagnetic Induction
Dec-2024
A magnet is moved towards a coil as shown in figure. Redraw the figure in your answer booklet and mark the direction of current in the coil. [1, 2]
Current in a circuit falls from 5 A to 0 A in 0.1 s. If an average emf of 200 V induced, calculate the self-inductance of the circuit. [3, 4]
(a) The unit of Self-Inductance is _______.
(b) Derive an equation for magnetic potential energy of a solenoid. [23, 24]
(a) The working principle of an ac generator is _______.
(b) With the help of a diagram, explain the working of an ac generator and derive an equation for emf inducted in it. [19, 20]
Dec-2023
Unit of mutual inductance is _______. [5, 6]
State laws of electromagnetic induction. [15, 16]
Coil carrying current acts as a bar magnet.
(a) Define self induction.
(b) Derive the expression for self inductance of a solenoid. [21, 22]
(a) The working principle of ac generator is _______.
(b) Briefly explain the working of ac generator.
(c) Draw the waveform output. [25, 26]
Dec-2022
Lenz’s law is in accordance with law of conservation of _______. [9, 10]
What is motional emf? Derive an expression for it. [11, 12]
With a diagram and necessary theory explain the working of A.C. generator. [13, 14]
Alternating Current
Dec-2024
Write the equation for power dissipated in LCR series circuit at resonance. [1, 2]
(a) An ac voltage V = Vₘ sin ωt is applied across a capacitor ‘C’, derive an equation for the instantaneous current.
(b) What is the average power consumed in the capacitor over a complete cycle of ac? [23, 24]
(a) Explain any two energy losses in a transformer.
(b) A 44 mH inductor is connected to 220 V, 50 Hz ac supply. Determine the rms value of the current in the circuit. [17, 18]
(a) Using the phasor diagram of an LCR series circuit (V_L > V_C), derive an equation for the impedance of the circuit.
(b) A series LCR circuit connected to a variable frequency source 230 V. L = 5 H, C = 80 µF and R = 40 Ω. Determine the source frequency which drives the circuit in resonance. [19, 20]
Dec-2023
The phase difference of current and voltage in a pure capacitive circuit is
(a) 0°
(b) 45°
(c) 60°
(d) 90° [5, 6]
How will you determine the power of ac circuit and explain power factor. [21, 22]
(a) What is a transformer? Explain its different types.
(b) Explain energy losses in a transformer. [27, 28]
(a) What is rms value of ac?
(b) Identify the components in ac circuit and draw its phasor diagram: [Circuit diagram showing Resistor, Inductor, Capacitor]
(c) Obtain the impedance in the circuit. [25, 26]
Dec-2022
In a capacitor only AC circuit the circuit current _______
(a) leads the applied voltage by 180°
(b) lags the applied voltage by 180°
(c) leads the applied voltage by 90°
(d) lags the applied voltage by 90° [9, 10]
What are the energy losses in a transformer? [9, 10]
What is capacitive reactance? Show its variation with frequency of the AC in a graph. [11, 12]
Capacitors, resistors and inductors are connected in series in many applications.
(a) Show a series LCR circuit in a figure.
(b) Using phasor diagram, find the formula for current of this circuit.
(c) Obtain expression for its impedance.
(d) What is power factor of this circuit? [13, 14]
Electromagnetic Waves
Dec-2024
Name the electromagnetic wave which is used in LASIK eye surgery. [1, 2]
What is displacement current? Write the expression for displacement current. [3, 4]
(a) Write any one use of Microwaves.
(b) A plane electromagnetic wave of frequency 25 MHz travels in free space along X-direction. At a particular point in space and time E = 6.3 j V/m, what is B at this point? [23, 24]
Dec-2023
The speed of electromagnetic wave is _______. [5, 6]
Electromagnetic spectrum consists of visible light, infrared rays, ultraviolet rays, γ-rays, X-rays and radio waves. Arrange them in the ascending order of their wavelength. [7, 8]
State and explain the displacement current. [21, 22]
Dec-2022
What is displacement current? Give its equation. [11, 12]
Ray Optics and Optical Instruments
Dec-2024
Telescopes with mirror objectives are called _______. [1, 2]
Draw the ray diagram corresponding to the image formation at ‘D’ in a compound microscope. (D – the least distance of distinct vision) [3, 4]
(a) Write lens Maker’s formula.
(b) Double-convex lenses are to be manufactured from a glass of refractive index 1.55, with both faces of the same radius of curvature. What is the radius of curvature required if the focal length is to be 20 cm? [23, 24]
(a) Derive the relation connecting focal length and radius of curvature of a spherical mirror.
(b) What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm? Is the system a converging or diverging lens? Ignore thickness of the lenses. [17, 18]
(a) Draw the ray diagram of refraction of light through a glass prism and derive equations for angle of prism A and angle of deviation ‘δ’.
(b) Draw the ray diagram of prism corresponding to minimum deviation. [19, 20]
Dec-2023
Draw the image formation at the near point of a simple microscope. [7, 8]
Explain critical angle and total internal reflection. [21, 22]
(a) Deduce lens makers’ formula.
(b) A double convex lens of radii curvatures 10 cm and 15 cm have a focal length of 12 cm. Find the refractive index of the material of the prism. [27, 28]
(a) State Snell’s law in refraction.
(b) Draw the path of a ray through a prism.
(c) Derive an expression for refractive index of the prism. [25, 26]
Wave Optics
Dec-2024
Which phenomenon of light supports its transverse nature? [1, 2]
What is the shape of the wave front in each of the following cases?
(a) Light diverging from a point source.
(b) Light emerging out of a convex lens when a point source is placed at its focus. [3, 4]
(a) Write the conditions for getting dark and bright bands in an interference pattern.
(b) In a Young’s double slit experiment, the slits are separated by 0.28 mm and the screen is placed 1.4 m away. The distance between the central bright fringe and the fourth fringe is measured to be 1.2 cm. Determine the wavelength of light used in experiment. [23, 24]
Derive Snell’s law of refraction of plane waves using Huygens’s principle. [17, 18]
Dec-2023
“The phenomenon of polarisation explains the transverse nature of light.” State the statement is True or False. [5, 6]
State Huygen’s principle of wave theory. [7, 8]
What are coherent sources and how they can be produced? [21, 22]
(a) What do you mean by polarisation?
(b) Write the expression for fringe width in interference pattern and mention each terms.
(c) Distinguish between interference and diffraction. [29, 30]