Heating effect of electric current

Made by- Group 4Group name- H.R HertzGroup leader- PragyanGroup members- 1. Aditya2. Anshul3.Bhisham4. Shubham

Electricity• Electricity is the most widely used form of energy

we cannot see electricity, but we can see its effects. The Electricity can produce different types of effects. Basically the effect of electricity is conversion of Electrical energy into other form of energy, such as Light, Heat etc.

• When electric current flows in a circuit, it produces various effects such as

• Heating Effect • Luminous Effect • Chemical Effect • Magnetic Effect• Out of the above four effects Heating effect and

magnetic effect are predominant. The heating effect of electricity is one of common and unique effect.our text here

Heating effect of electric current

• When a potential difference or Voltage is applied across the ends of a conductive metallic wire, the free electrons begin forced to move. When the electrons move the electrons collide with the atoms. In these collisions, energy of the electrons is transferred to the atom and the atoms begin to vibrate more violently.

• As a result of this collusion heat is produced. Greater the number of electrons flowing per second, greater will be the rate of collisions and hence more heat is produced.

• This effect of electricity is called the “Heating Effect” of electricity. The amount of heat produced by electrical device in unit time depends on the :-

I. Resistance offered by the electrical device (circuit) and

II. Amount of current flowing through the electrical device (circuit) and

III. The time (duration) of electric current flow.

Joule’s Law• In studies James Prescott Joule found that the heat produced by a

heating element is directly proportional to the square of the electric current (I) passing through the conductor,

• H α I2 (Current)• And directly proportional to the resistance (R) of the conductor, • H α R (Resistance)• time (t) for which current passes through the conductor.• H α t (Time)• Joule’s concluded that the quantity of heat developed in a current

carrying conductor is equal to the product of the square of the electric current, the resistance of the conductor and the time of flow of current through the conductor. If I is the current in ampere (A), R the resistance of the conductor in ohm (Ω), t the time in seconds (s) then the heat H produced in joule (J), is

• H = I2Rt• Using Ohm's law R=I/V, the above equation can be changed into

different forms.•

H = VI t

Applications of heating effect of electric current

• If we pass a current through a high resistive load higher amount of heat energy can produced by conversion of electric energy. This effect to electric current is used in many electrical appliances.

• The heating effect of electric current is utilized in many electrical heating appliances such as Electric Iron, Room Heater, Water Heater (Immersion Rod), Heater etc. All these appliances contain high resistance coils. These high resistance heating coils are made up of nichrome, an alloy of nickel, chromium, manganese and iron. The reasons for using nichrome as a heating coil are

I. High melting pointII. High resistanceIII. The coil can remain in red-hot condition for a long time.

• When the appliances are connected with Electric Supply then a large amount of heat is produced in the heating coils because of high resistance of connected of nichrome wire.

Bulb• We see a thick metallic wire in the bulb. It

is made of tungsten metal. In a glass vessel or bulb the tungsten wire is kept sealed. The glass bulb is filled with neutral gas or vacuum. Neutral gases are using now a days commonly. The tungsten wire is known as filament when the current flows through the tungsten wire or filament it becomes heated and emit light. Due to the flow of current heating effect of an electric current used as the source of light.

Electric Iron• The conversion of electrical

energy into heat energy is used in “Electric Iron”.

• Construction: • The simple electric iron uses an

element made of Nichrome strip insulated by mica. When the current flows through the nichrome stripped wire, a heat produces and this heat makes the bottom of electric iron hotter. This heat is used for ironing of cloths.

Heater• The conversion of electric energy into

heat is achieved by a process called electric heating. Electric heaters are used for this conversion process. Electric heating finds many applications in industrial as well as in cooking processes. For example if we consider electric heaters, its working is very simple. It consists of an electrical resistor in it.

• The electric heater works on the principles of Joule’s law of heating. According to this principle, when electric current is passed through the resistor, then the conversion of electric energy into heat energy takes place.

Fuse• In different types of electrical

instruments fuses are used in our houses. In any electric circuit, in electric line, if there is a sudden high rise of current, then those instruments can be burnt down or there can be fire. The reason for this sudden high rise of current is the short circuit between two terminals of the electrical line. A low melting point conducting wire is connected in series to avoid this type of accident.

Questions• According to Joule’s law how can we find the heating

effect of electric current? • H = I2Rt H = VI t

• Which metal is used to make the filament of a light bulb?• Tungsten

• What is used as an element to heat the electric iron?• Nichrome coated with mica

• What are the reasons for using nichrome wire as a heating element?

I. High melting pointII. High resistanceIII. The coil can remain in red-hot condition for a long time.

Thank you