2018-2019 February

When a sparingly soluble substance like alcohol is dissolved in water, surface tension of water

increases

decreases

remains constant

becomes infinite

Concept: Surface Tension

The specific heat capacity of water is

8R

`7/8R`

9R

`9/7R`

Concept: Specific Heat Capacities - Gases

The electric field intensity outside the charged conducting sphere of radius ‘R’, placed in a medium of permittivity ∈ at a distance ‘r’ from the centre of the sphere in terms of surface charge density σ is

`σ/∈ (R/r)^2`

`σ/∈ (r/R)^2`

`σ/∈ (R^2/r^2)^2`

`σ/∈ (r^2/R^2)^2`

Concept: Applications of Gauss’s Law

An electron of energy 150 eV has wavelength of `10 ^-10m`. The wavelength of a 0.60 keV electron is

Concept: de-Broglie Relation

What is the value of tangential acceleration in U.C.M. ?

Concept: Angular Acceleration

What happens to a ferromagnetic substance heated above Curie temperature ?

Concept: Curie Temperature

At which position of the plane of the rotating coil with the direction of magnetic field, the e.m.f. induced in the coil is maximum ?

Concept: Van-deGraaff Generator

Name the logic gate which generated high output when at least one input is high.

Concept: Digital Electronics and Logic Gates

In Young’s experiment interference bands were produced on a screen placed at 150 cm from two slits, 0.15 mm apart and illuminated by the light of wavelength 6500 Å. Calculate the fringe width.

Concept: Interference of Light Waves and Young’S Experiment

The susceptibility of magnesium at 300 K is 1.2 x 10^{ -5} . What will be its susceptibility at 200 K.

Concept: Curie Temperature

The length of the second’s pendulum in a clock is increased to 4 times its initial length. Calculate the number of oscillations completed by the new pendulum in one minute.

Concept: Periodic and Oscillatory Motions

Define capacitance of a capacitor and its SI unit.

Concept: The Parallel Plate Capacitor

Define radius of gyration. Write its physical significance.

Concept: Definition of M.I., K.E. of Rotating Body

Distinguish between p-type and n-type semiconductors.

Concept: Electrical Properties - Applications of N-type and P-type Semiconductors

Explain the terms (a) Transducer and (b) Attenuation in communication system.

Concept: Elements of a Communication System

Obtain expressions of energy of a particle at different positions in the vertical circular motion .

Concept: Vertical Circular Motion Due to Earth’s Gravitation

Define binding energy and obtain an expression for binding energy of a satellite revolving in a circular orbit round the earth.

Concept: Binding Energy and Escape Velocity of a Satellite

State Hooke’s law. Define elastic limit and modulus of elasticity.

Concept: Hooke’s Law

Obtain an expression for the rise of a liquid in a capillary tube.

Concept: Capillarity and Capillary Action

Explain the reflection of transverse and longitudinal waves from a denser medium and a rared medium.

Concept: Reflection of Transverse and Longitudinal Waves

What is photoelectri effect ? Defin (i) Stopping potential (ii) Photoelectric work function.

Concept: Photoelectric Effect - Hertz’S Observations

What is perfectly black body ? Explain Ferry’s black body.

Concept: Qualitative Ideas of Blackbody Radiation

When a resistor of 5Ω is connected across the cell, its terminal potential difference is balanced by 150 cm of potentiometer wire and when a resistance of 10 Ω is connected across the cell, the terminal potential

difference is balanced by 175 cm same potentiometer wire. Find the balancing length when the cell is in open circuit and the internal resistance of the cell.

Concept: Potentiometer

A cyclotron is used to accelerate protons to a kinetic energy of 5 MeV. If the strength of magnetic field in the cyclotron is 2T, find the radius and the frequency needed for the applied alternating voltage of the cyclotron. (Given : Velocity of proton= `3xx10^7 m//s`)

Concept: Motion in Combined Electric and Magnetic Fields - Cyclotron

Assuming expression for impedance in a parallel resonant circuit, state the conditions for parallel resonance. Define resonant frequency and obtain an expression for it.

Concept: Forced Oscillations and Resonance

Using an expression for energy of electron, obtain the Bohr’s formula for hydrogen spectral lines.

Concept: Hydrogen Spectrum

State the law of radioactive decay. hence derive the relation t N = Noe^{-λt} . Represent it graphically. `l`

Concept: Radioactivity - Introduction of Radioactivity

Show that even as well as odd harmonics are present as overtones in the case of an air column vibrating in a pipe open at both the ends.

Concept: Study of Vibrations of Air Columns

A wheel of moment of inertia 1 kg.m^{2} is rotating at a speed of 30 rad/s. Due to friction on the axis, it comes to rest in 10 minutes. Calculate the average torque of the friction.

Concept: Study of Vibrations of Air Columns

Explain the formation of stationary waves by analytical method. Show that nodes and antinodes are equally spaced in stationary waves.

Concept: Formation of Stationary Waves on String

The radius of gyration of a body about an axis, at a distance of 0.4 m from its centre of mass is 0.5 m. Find its radius of gyration about a parallel axis passing through its centre of mass.

Concept: Definition of M.I., K.E. of Rotating Body

Obtan an expression for potential energy of a particle performing S.H.M. What is the value of potential energy at (i) Mean position, and (ii) Extreme position

Concept: K.E.(Kinetic Energy) and P.E.(Potential Energy) in S.H.M.

A stretched sonometer wire is in unison with a tuning fork. When the length of the wire is increased by 5%, the number of beats heard per second is 10. Find the frequency of the tuning fork

Concept: Study of Vibrations in a Finite Medium

From differential equation of linear S.H.M., obtain an expression for acceleration, velocity and displacement of a particle performing S.H.M.

Concept: Differential Equation of Linear S.H.M.

A sonometer wire 1 metre long weighing 2 g is in resonance with a tuning fork of frequency 300 Hz. Find tension in the sonometer wire.

Concept: Study of Vibrations in a Finite Medium

Explain refraction of light on the basis of wave theory. Hence prove the laws of refraction

Concept: Reflection and Refraction of Plane Wave at a Plane Surface Using Wave Fronts

Two coherent sources of light having intensity ratio 81 : 1 produce interference fringes. Calculate the ratio of intensities at the maxima and minima in the interference pattern.

Concept: Interference of Light Waves and Young’S Experiment

State Brewster’s law and show that when light is incident at polarizing angle the reflected and refracted rays are mutually perpendicular to each other.

Concept: Brewster's Law

Monochromatic light of wavelength 4300 Å falls on a slit of width ‘a’. For what value of ‘a’ the first maximum falls at 30° ?

Concept: Fraunhofer Diffraction Due to a Single Slit

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