PHYSICS IMPORTANT POINTS FOR +2 EXAMS AND MEDICAL ENTRANCE TESTS

Lenz’s law is based on the law of conservation of energy. The core of a transformer is made laminated to avoid the energy

loss due to eddy currents. A step up transformer converts low voltage AC to high voltage AC,

whereas a step down transformer converts high voltage AC to low voltage AC.

A transformer works on the principle of mutual induction.

Electromagnetic waves consist of electric field vector ⃗⃗ and

magnetic field vector ⃗⃗ ⃗ mutually perpendicular to each other. Electromagnetic waves are the transverse waves which travel

with the speed of light. In Young’s double slit experiment, the relation for fringe width is

given by, β = Dλ / d, where β = fringe width, D = distance between slits and screen, d = distance between the double slits.

Bending of light waves around the edges of an obstacle is called diffraction.

A particle having zero charge and zero mass but having energy is called a photon.

In amplitude modulation, the amplitude of the carrier wave varies in accordance with the amplitude of the modulating signal.

The radio waves after refracting from different parts of ionosphere, on reaching the earth, are called sky waves.

Energy released per nuclear fission is 200MeV while that released per nuclear fusion is 26.7 MeV. (1amu = 931 MeV)

In common emitter transistor amplifier, the input signal voltage and the output signal voltage are out of phase by an angle of 180 degree.

A rectifier is a device which converts AC current/voltage into DC current/ voltage. A p - n junction diode is used as a rectifier.

Zener diode is used as a voltage regulator; it is operated in reverse breakdown voltage.