SOUND  Sound waves are characterised by the motion of particles in the medium and are called mechanical waves.  Whe…

WORK AND ENERGY  Two conditions need to be satisfied for work to be done: (i) a force should act on an object, and (i…

GRAVITATION  The change in direction involves change in velocity or acceleration.  The force that causes this accel…

FORCE AND LAWS OF MOTION  An object moves with a uniform velocity when the forces (pushing force and frictional force…

MOTION  The shortest distance measured from the initial to the final position of an object is known as the displaceme…

CONVENTIONAL SOURCES OF ENERGY Fossil Fuels:-  fossil fuels – coal and petroleum.  But these fuels were formed over m…

Magnetic Effects of Electric Current  A compass needle is a small magnet. Its one end, which points towards north, is…

Practical Applications of Heating Effect of Electric Current  The generation of heat in a conductor is an inevitable c…

REFLECTION OF LIGHT  The angle of incidence is equal to the angle of reflection, and  The incident ray, the normal to…

 Light travels along straight lines.  Any polished or a shining surface acts as a mirror.  An image which can be obt…

 Our sense of touch is not always a reliable guide to the degree of hotness of an object.  Temperature is a measure o…

International System of Units (SI)  SI is the modern from of the metric system and is the world’s most widely used sys…