2. ACKNOWLEDGEMENT
I am grateful to my Physics teacher
Mrs. for her guidance and constant
supervision as well as cooperation in
providing all the necessary information
regarding the portfolio.
3. Introduction
What is the Heating Effect of Electric Current?
Effects of Heat on the Conductor
Heating Effect of Electric Current Formula
Joules Law of Heating
Factors on which Heat Depends
Applications of Heating Effect of Electric Current
INDEX
4. Introduction
When an electric current is allowed to flow
through a high resistance wire, such as
nichrome wire, the conductor heats up and
produces heat. Such a heating action of a
conductor is known as the Heating effect of
Current.
5. What is the Heating Effect of
Electric Current?
When we use some electrical appliances, the chemical reactions which occur in
the cells on which they run generate some potential difference between its
terminals which sets the electrons in motion. To maintain the flow of current
the source needs to expand some energy. A part of the energy is used in doing
some sort of useful work like moving the fan blades in case of electricity-
generated fans, etc. The remaining energy is exploited or expanded in the form
of heat which raises the temperature of the appliance. If we are using a circuit
in an appliance that is purely resistive then a lot of energy is dissipated entirely
in the form of what we call heat. This is called or known as the heating effect of
electric current.
6. Effects of Heat on the Conductor
• The heating effect may cause an increase in the temperature of the wire of the
conductor.
• This may also cause an increase in the volume of the material.
• More simply, when an electrical current is passed through a conductor, it generates
excess heat due to the resistance caused by the electrons in the conductor to the
flowing current. The work done in overcoming this resistance to the current
generates what we call heat in that conductor. The electrical heating effect of the
electrical current is most commonly and widely applied and used in our daily life.
For example, electrical irons, kettles, toasters, electrical heaters, etc. are used widely
as alternatives to conventional methods of cooking and also laundry. This same
effect is used widely in electrical bulbs which are alternatives to conventional
incandescent lamps. These devices have modernized and revolutionized the new
sustainable world over the years.
7. Heating Effect of Electric Current Formula
• Let us assume a current I that is flowing through a resistor that
has a resistance of R as shown in the circuit. Let the potential
difference across ends of the terminals of the battery be V. Let
us assume to be the time during which a charge of Q amount
flows across the circuit. The work which is done in moving that
charge Q through a potential difference V is V × I.
• Hence, the source has to supply energy equal to V × I in time t.
Therefore, the power input to the electrical circuit by the
source is
• P = V × Q/t
• = V × I
• Or the energy that is being supplied to the circuit by the
source in time t is P × t, that is, V × I × t. This extra energy
generated gets dissipated in the resistor in the form of heat.
Therefore, for a steady and fixed current I, the amount of heat
denoted by H that is produced in time t then:H = V × I × t
8. Joules Law of Heating
The very famous physicist James Prescott found that the amount of heat
generated per second that develops in a conductor having a current is directly
proportional to the electrical resistance of the wire and also with the square of
the current given. This heat which is liberated or generated because of the
electrical current that flows in an electrical wire is expressed in Joules.
By applying the ohms law to the equation H = V × I × t. We can deduce the Joules
law or joules first law which gives the relationship between the heat that is
produced by flowing charges of electric current through a conductor. It is
directly proportional to the square of the supplied current, the electrical
resistance exerted by the appliance, and the time for which we used it. This is
known or called joule’s law of heating. The following is its expression:
H = I2 × R × t
9. Factors on which Heat Depends
• The amount of liberated or generated heat is directly
proportional to the given wire’s electrical resistance when the
electrical current in the given circuit and the flow of supplied
current is not altered or changed.
• The amount of liberated or generated heat in the conductor
carrying current is directly proportional to the square of the
electrical current that flows through the given circuit when the
electrical resistance and current supply is kept constant.
• The amount of heat generated or produced because of the
electrical current flow is directly proportional to the time of
usage of flow when the electrical resistance and the current flow
is constant.
10. Applications of Heating Effect of Electric
Current
• Electric Iron
• Electric Heater
• Electric Fuse
• Electric Bulb
