Electric Energy—

The energy of a voltage source to flow a constant current through a resistor for a given time is called Electric Energy consumed in the circuit.

Let a voltage source ‘V’ supplies current ‘I’ through a resistor ‘R’, then         

The unit of Electrical Energy is ‘Watt-second’.

Heating Effect of Current--

When a resistor is connected with a voltage source, electrons start flow from negative electrode to positive electrode through this resistor and energy of the source gets dissipated in the form of heat produced in the resistor. This phenomenon is called heating effect of current.

 Let we have a resistor ‘R’ which is connected to a Battery of voltage ‘V’ so that current ‘I’ flows Through it. Amount of charge flows through R in time t(q)=It

Amount of  work done to flow charge ‘q’ through Resistor (W) =  qV

Superconductivity—

As we know the velocity of the electrons in the conductors increase as the temperature increase, so, the number of collision between the electrons also increases. As a result resistance of the conductor also increases. This relation is given by

Drift Velocity—

The drift velocity is defined as the average velocity gained by the free electrons of a conductor in the opposite direction of the externally applied electric field.

Relaxation Time—

The average time that elapses between two successive collisions of an electron is called relaxation time.