Physics: Multiple Choice and Short Answers

• Full marks are 75, and the time allocated is 3 hours.

Group A: Multiple Choice Questions

• The product of the moment of inertia and angular velocity results in angular momentum.
• A simple pendulum with a 0.40 kg bob oscillates with a 2.0 s period and a 0.15 m amplitude; its kinetic energy at the mean point is 0.044 J.
• Earthquakes are caused by the rubbing together of Earth's plates.
• After 4 half-lives, 6% of the original radioactive atoms remain.
• Air temperature changes affect the wavelength of sound.
• The internal energy of an ideal gas depends on temperature.
• Maximum work is done in an Isothermal process of a gas.
• Given a neutral temperature of 500°C at a cold junction of 0°C, the percentage change in the temperature of inversion is 4% when the cold junction is at 20°C.
• Maximum power dissipation occurs in a purely resistive circuit.
• Laminated cores are used in transformers to reduce eddy current.

Group B: Short Answer Questions

• Simple Harmonic Motion: Define simple harmonic motion.
• Time Period Derivation: Derive the time period of oscillation for a mass m attached to a vertical spring with force constant k.
• Time Period in Satellite: Determine the time period of the mass-spring system inside a satellite.
• Bernoulli's Principle: State Bernoulli's principle.
• Liquid Flow: A liquid with a density of 1200 kg/m³ flows through a tube. At point A (1.0 cm²) the speed is 10 cm/s. Point B has an area of 20 mm².
  • Speed at B: Calculate the speed at point B.
  • Pressure Difference: Calculate the pressure difference between points A and B.
• Petrol Engine Diagram: Draw a PV diagram for a petrol engine and explain its operation.
• Engine Efficiency: Compare the efficiency of petrol and diesel engines based on compression ratios.
• Sonometer Frequency: A 75 cm sonometer wire resonates with a tuning fork. Shortening the wire by 0.5 cm produces 3 beats. Calculate the tuning fork's frequency.
• String Vibration: An experiment measures the speed of sound in a string, where the vibrator's frequency is 120 Hz.
  • Progressive Wave Speed: Calculate the speed of a progressive wave along the string.
• Lenz's Law: State Lenz's law.
  • Conservation of Energy: Explain how Lenz's law supports energy conservation.
• Induced Current Direction: Determine and explain the direction of induced current in two coils (C1 and C2) when a magnet moves between them.

Group C: Long Answer Questions

• Diode in Rectification: A diode is used as a rectifier.
  • Diode Characteristic: Identify the characteristic of a diode used in rectification.
  • Full Wave Rectifier: Draw a circuit diagram of a full-wave rectifier.
  • Logic Gate Truth Table: Construct a truth table for the provided circuit with NOR, OR, AND, and NAND gates, including states at E, F, and G.
• Negative Energy: Significance of the negative energy of an electron in orbit.
• Atomic Transition: Energy levels of an atom are provided.
  • Wavelength Calculation: Determine which transition results in a 275 nm photon emission, including calculations.
• Hydrogen Atom Wavelength: Find the expression for the emitted wavelength when an electron transitions between energy levels n₂ and n₁.
• Balmer Series: Calculate the magnitude of the wavelength of the second Balmer series, given R = 1.09 x 10^7 m⁻¹.
• Wavelength Measurement: A student measures the wavelength of green light (546 nm) using a double slit (0.50 mm separation) and a diffraction grating (3000 lines/cm).
  • Fringe Width: Calculate the width of ten fringes on a screen 0.80 m away.
  • Second-Order Angle: Calculate the angle of the second-order maximum using the grating.
  • Experiment Accuracy: Determine which experiment provides a more accurate wavelength measurement.
• Polaroid Sunglasses: Differentiate between polaroid and non-polaroid sunglasses.
• Polarization Angle: Calculate the angle of incidence at which light from water (μ = 1.3) is completely polarized.
• Sound Intensity: Describe how the intensity of sound changes when the distance from the source increases fourfold.
• Train Whistle Frequency: A train travels at 30 m/s emitting a 262 Hz whistle; another train moves in the opposite direction at 18 m/s.
  • Approaching Frequency: Calculate the frequency heard when approaching the first train.
  • Receding Frequency: Calculate the frequency heard when receding from the first train; the velocity of sound is 340 m/s.
• Sinusoidal Sound Wave: In a moderately loud sound wave, maximum pressure variations are 3.0 x 10⁻² Pa, and the frequency is 1000 Hz.
  • Maximum Displacement: Calculate the maximum displacement, given the speed of sound (344 m/s) and bulk modulus (1.42 x 10⁵ Pa).
• Choke Coil: Define what a choke coil is.
• AC Circuit Preference: Explain why a choke coil is preferred over a resistor in an AC circuit.
• AC Circuits: Three AC circuits (a, b, c) with equal currents are shown. If the frequency of the EMF is increased, explain what effect this will have on the currents flowing through them.
• Opposition Comparison: Explain what difference to expect in the opposition when provided by circuits for current now in figures a and b.

Alternative Questions

• Ampere Definition: Define 1 Ampere in terms of the force between two parallel current-carrying conductors.
• Solenoidal Coil Contraction: Explain the contraction of a solenoidal coil when current passes through it.
• Conductor in Magnetic Field: A conductor with a linear mass density of 0.2 g/m is suspended in a magnetic field of 1T.
  • Current Calculation: Compute the current inside the conductor, assuming zero tension in the supporting wires.
  • Torque Calculation: Calculate the torque produced if the current passes through a 100-turn coil with a 100 cm² area held perpendicular to a 10 T magnetic field with the plane parallel to the field.