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If two identical progressive waves propagating in opposite directions superpose each other then the resultant wave will be in the form of continuous loops and no energy is transferred in the medium.

Stationary waves

When a compressional wave is sent through an open pipe ,it gets reflected at the end of the pipe . these incident and reflected waves with same frequency in opp direction superimpose each other along the length of the pipe

Standing wave in open closed pipe

If a vibrating tuning fork is kept at the open end of the pipe, then compressions and rarefactions starts moving inside the pipe and gets reflected and incident waves superpose with each other and stationary waves are formed

Closed pipe

The apparent change in frequency of sound when there is a relative motion between source and the observer

Doppler effect

It is a property of virtue by which the nucleus of a heavy element disintegrates itself by emitting radiation without any external agents influence

Radioactivity

The rate of radioactive decay at any instant is directly proportional to the no. of nuclei present at that instant

Radioactive decay law

It is a device used to produce nuclear energy due to nuclear fission. works on the principle of controlled chain reaction.

Nuclear reactor

1.fuel 2.moderator 3.control rods 4.shielding 5.coolant

5 essential features of a nuclear reactor

When a steady current flows through a wire of uniform cross section ,the potential difference between any two points of the wire is directly proportional to the length of the wire

Principle of potentiometer

When a ray of light passes from a denser medium to a rarer medium , the refracted ray bends away from the normal. as the angle of incidence increases the angle of refraction also increases, and for the angle of incidence for which the angle of refraction is 90 is called critical angle.

Critical angle

When a light ray is passed from a denser to rarer medium with an angle of incidence greater than the critical angle reflects back into the denser medium,obeying the laws of reflection.

Total internal reflection

It is an optical illusion caused by atmospheric refraction. on a still hot day travellers on a tarred road or in desserts get the impression of pool of water on the road.

Mirage

The coloured arcs or the spectrum of white light from the sun on the form of bows observed immediately after rain the formation of rainbow is combined effect of reflection ,refraction and dispersion of light in the water droplets when light from the sun falls on it.

Rainbow and formation

Light from the sun after dispersion from the water droplets reaches the observer after suffering 'one internal reflection' violet in the inner edge and red in outer intensity is more

Primary rainbow

Light from the sun after undergoing dispersion from the water droplets reaches the observer after suffering 'two internal reflections' red on the inner edge and violet on the outer fainter

Secondary rainbow

At sunset or sunrise, the sun rays have to pass through a greater distance in the atmosphere. most of the shorter wavelengths are removed by scattering as scattering of light is inversely proportional to the 4th root of wavelength . and the least scattered red light reaches our eye .

Reddish appearance of the sun

A convex lens of small focal length can be used to see magnified images of small objects.

Simple microscope

When a star moves away from the earth with high velocity , the frequency of the light emitted by the star decreases and the wave length increases, thus its spectral lines shift towards the red end of the spectrum

Red shift

When a star moves towards the earth with high velocity, the frequency of the light emitted by the star increases and the wavelength decrease. thus its spectral lines shift towards the blue end of the spectrum .

Blue shift

The total electric flux through any closed surface is equal to 1/e times the net charge enclosed by that surface

Guass's law

The magnitude of the electrostatic force of attraction or repulsion between any two point charges is directly proportional to the product of the magnitude of the charges and inversely proportional to the square of the distance between them.

Coulomb's law

The line integral of the magnetic field of induction B around any closed path in vaccum or air is equal to the permeability of free space in vaccum time the total current enclosed by the closed path.

Ampere's law

The intensity of magnetic field of induction dB at a point due to an element is directly proportional to the length of the element, current passing through the element , sine of the angle between the element and the position vector of the point and inversely proportional to the distance between the element and the point.

Biot savart's law

Loops of electric current induced within the conductor by the change of magnetic field in the conductor ,according to faraday's law induction.

Eddy current

Induction furnaces,induction motors,eddy brakes, energy meters, speedometer, fault detection in components

Advantages of eddy current

Spectra of atoms having more than one electron arrangement of electrons in an orbit rate of transition of electrons fine structure of atom chemical bonding zeeman and stark effect

Limitations of bohr's theory

V=R(1/n1^2-n2^2) Lymen - UV region Balmer - visible region Paschen - near the IR Bracket - in the IR Pfund - far from IR

Spectral series in H atom (LBPBP)

The process of converting alternating current (AC) into direct current(DC)

Rectification

The angular momentum of a moving electron is an integral multiple of h/2pi

De broglie's explanation of bohr's second postulate

Defect of the eye where it can only see distant objects clearly. convex lens 1/f=1/D-1/d

Hypermetropia

Defect of the eye where it can only see the nearer objects clearly. concave lens of focal length equal to the far point .

Myopia

The splitting for white light into seven colours on passing through a refracting medium, violet disperses more

Dispersion

Temperature coeff of resistance

It is defined as the ratio of increase in resistance per degree centigrade rise in temperature to its resistance at 0C

Gauss law for magnestism

States that no magnetic monopoles exists and that the total flux through any closed surface must be zero.

Angle of declination

The angle between the magnetic meridian and the geographical meridian

Angle of inclination/angle of dip

The angle made by the total strength of the earths magnetic field with the horizontal line of magnetic meridian

Lenz's law

The direction of induced emf is such that it tends to oppose the change in magnetic flux that produced it.

Faraday's law of electromagnetic induction

The emf induced in a conducting loop is equal to the rate at which the magnetic flux in the conducting loop changes with time

Power factor

The cosine of the phase angle between the voltage and current in an ac circuit. cos=R/Z

Uses of IR rays

Molecular structure night time photography solar cookers/heaters physiotherapy

Uses of microwaves

Radar systems long distance com ovens

Production of microwaves

By special vaccum tubes like klystron, maagnetron, gunn diode

Coercivity

Is the intensity of the magnetic field applied to reduce the magnetization to zero

Retentivity

It is the capability to retain magnetism after the magnetization force has been ceased

Work function

The minimum amount of energy of incident photon required to eject electrons from the surface of a photometal

Photoelectric effect

The phenomenon of emission of electrons from the surface of a metal ,when a radiation of suitable frequency is incident on it

Photosensitive substances

Alkali metals because their work function is low

Isobars

Same atomic number but different atomic mass

Isotopes

Same mass number ,diff atomic number

Istones

Same neutron number , different atomic number

Amplifier

The device used to rise the strength of a weak signal

Mobile phone

Space wave com

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