Meter-Bridge Null Point Calculation and AC Circuit Peak Current

Meter Bridge

• Unknown resistance X in the left gap and 30 Ω in the right gap of a meter-bridge, null point is obtained at 40 cm from the left end of the wire.
• When resistance in each gap is increased by 15Ω, calculate the unknown resistance and shift in the position of the null point.

Inductor and A.C. Source

• Inductor of inductance 200 mH is connected to an A.C.source of peak e.m.f. 210 V and frequency 50 Hz.
• Calculate the peak current and instantaneous voltage of the source when the current is at its peak value.

Theorem of Parallel Axes

• State and prove theorem of parallel axes.

Thermodynamic Processes

• Define:
  • Isothermal process
  • Adiabatic process
• One mole of an ideal gas is enclosed in an ideal cylinder at 1.0 mPa and 27°C. The gas is allowed to expand till its volume is doubled.
• Calculate the work done if the expansion is isobaric.

Fluid Dynamics

• Distinguish between streamline flow and turbulent flow.
• Calculate the terminal velocity with which an air bubble of diameter 0.4 mm rises through a liquid of viscosity 0.1 Ns/m2 and density 900 kg/m3. Density of air is 1.29 kg/m3.

Fraunhofer and Fresnel Diffraction

• Define:
  • Fraunhofer diffraction
  • Fresnel diffraction
• A plane wavefront of light of wavelength 5500Å is incident onto a slit perpendicular to the direction of light rays.
• Calculate the distance between the slits if the total separation of 10 bright fringes on a screen 2 m away is 2 cm.

Transformers and Eddy Currents

• Define:
  • Transformer
• Derive an expression for electric field intensity due to an infinitely long straight charged wire.
• Define eddy currents and write two applications.

Inductive and Capacitive Reactance

• Define and state formulae for:
  • Inductive reactance
  • Capacitive reactance

Work and Energy

• Draw a p –V diagram and explain the concept of positive work done and negative work done.

Vibrating String

• State the law of length and the law of linear density for a vibrating string.

Moving Coil Galvanometer

• For a moving coil galvanometer, show that S = G , n 1 where S is shunt resistance, G is galvanometer resistance, and n is the ratio of total current to the full scale deflection current.

De-Broglie Wavelength

• The de-Broglie wavelengths associated with an electron and a proton are the same.
• Calculate the ratio of their kinetic energies.

Radioactive Decay

• Derive an expression for 'Half Life Time' of a radioactive material using the ‘Law of Radioactive Decay’.

Motorcyclist Stunt

• A motorcyclist performs a stunt along the cylindrical wall of a ‘Well of Death’ of inner radius 4 m.
• Coefficient of static friction between the tyres and the wall is 0.4.
• Calculate the maximum period of revolution.

Water Drop Diameter

• Calculate the diameter of a water drop if the excess pressure inside the drop is 80 N/m2.
• Surface Tension of water = 7.2 × 10–2 N/m