## Note on Heating and Lighting Effect of Current Electricity

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There are various uses of electricity in our daily life. We use electricity to light our homes, heat our rooms, to electroplate metals and many more. While using electricity, we are basically converting electrical energy to various forms according to our need. These conversions of energy can also be regarded as the effect of electricity. There are various effects of current and we will talk about two of those in here.

1. Heating effect:

Though a conductor can easily conduct electricity it also resists the flow in some way. The resistance is due to the atoms of the conductors. The atoms are not arranged in a linear form and are scattered (and they are moving randomly so may collide with the electric charge flowing in the wire) in the wire. So there is a significant obstruction to the movement of electricity. This resistance can produce the heating effect. When colliding with each other, they produce heat. This heating effect can be increased by use of the heating element. The heating element is the special coil made from Nichrome wire. Nichrome wire, made from an alloy of nickel wire and chromium wire, though a conductor possesses significant resistance. It also has a high boiling point and do not react with atmospheric oxygen at high temperature so can be heated to high temperature.

2. Lighting Effect:

Lighting effect of electricity can be achieved by various ways. We will study mostly two ways we get the lighting effect of electricity.

#### Filament lamp:

The mechanism of lighting is also similar to the heating effect. When the wire gets hot due to the resistance it produces heat and light at the same time. But we can use a different alloy of metals to get more lighting effect than heating effect. For more heating effect we used Nichrome but for light, we have to use Tungsten metal. Tungsten metal has higher resistance it can be heated up to 33000°C as it melts at 34000°C. But tungsten metal reacts with atmospheric oxygen when heated, so it has to be enclosed in glass bulb with an inert gas, Nitrogen or Argon, with it. Instead of filling with inert gas the bulb can be made a vacuum. Out of the total energy, only 10% is converted into the light energy and rest is converted into heat.

#### Fluorescent lamp:

The lighting mechanism of the fluorescent lamp is different from the filament lamp. The fluorescent lamp has a coating of fluorescent powder inside its glass. The lamp is filled with mercury vapor from inside and sealed with two sticking electrodes in each side. The electricity is carried from one electrode to another electrode through mercury vapors. When the electricity flows through the bulb the electrons excite mercury vapors and the excited mercury vapor emits ultraviolet rays. Those ultraviolet rays, when to strike with the inner coating of the bulb, produce visible light. Since we use mercury vapor in the tube it is also called mercury bulb (tube).

• Uses of electricity in our daily life: light our homes, heat our rooms, to electroplate metals etc.
• Heating effect can be increased by use of the heating element. A heating element is a special coil made from Nichrome wire. Nichrome wire, made from an alloy of nickel wire and chromium wire, though a conductor possesses significant resistance. It also has a high boiling point and do not react with atmospheric oxygen at high temperature so can be heated to high temperature.
• Lighting effect of electricity can be achieved by various ways. We will study mostly two ways we get the lighting effect of electricity. (Filament lamp, Fluorescent lamp)
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### Very Short Questions

The temperature of wire increases when electricity is passed through a wire,. This is called heating effect of electricity. Heating effect of electricity depends upon time, resistance and strength of electric current. Thus, electric current can be converted into heat energy by high resistance wire .For example, electric heater; electric kettles are used to warm up water.

A nichrome wire can be used as heating element for an electric heater because of following reasons: -

• It has high melting point.
• It has high resistance which helps converting most of the electrical energy into heat energy.

When electric current is passed through a conductor, it becomes very hot due to which it emits light. This is called lighting effect of electric current. For example: electric bulbs, fluorescent lamps, etc.

The resistance of the coil changes with the thickness of the coil, as $$R\propto\frac{1}{t}$$. For thick coil the resistance will be smaller and for the filament, the resistance of the wire should be very high. In order to increase the resistance to high value, one of the methods is to decrease the diameter of the wire. Hence, the diameters of the filaments are made very small to get higher resistance.

A coil of wire have high resistance used in electrical heater, room heater is known as heating element. Nichrome wire is usually used as a heating element.

Nichrome wire is used as heating element because it has got high resistance and does not react with oxygen even at the higher temperature of 9000C. When we pass electricity into the material having high resistance, heat energy is produced.

Filament is the thin piece of wire kept in the filament lamp which glows to give light when electricity is passed through it. Tungsten is used as filament because it has got high resistance and high melting point of 34000C. When electricity is passed in it, it is heated to whiteness and produce light-energy.

Filament has high melting point (3400 degree C) and high resistance. As the filament possesses high resistance, it converts electrical energy into heat and light energy. The other wires have low resistance. Due to this reason filament glows with bright light but it doesn't happen in other wire when electric current is passed.

Tungsten metal is used as filament inside the electric bulb because it has high melting point (3400 degree C) and high resistance.

Any two differences between filament and fluorescent lamp are as follows:

 Filament lamp Fluorescent Lamp Its life duration is about 1000 hours. Its life duration is about 3000 hours. It is filled with inert gases like argon and nitrogen. It is filled with mercury vapour.

In electric bulbs, tungsten metal is used as filament and it gets heated up to about 2900 degree C. At such a high temperature, tungsten reacts with oxygen to get oxidized and bulb gets damaged. So, to avoid oxidation of tungsten filament, electric bulbs (Filament lamp) are filled with inert gases like argon and nitrogen.

If air is enclosed inside the bulb, during burning filament reacts with oxygen on air. Then filament gets converted to metal oxide and breaks. Then, the bulb becomes useless. Therefore, air is not enclosed inside the bulb.

Although the power of both lamps is same, the efficiency of filament lamp is less than that of fluorescent lamp so the brightness of filament is less than that of fluorescent lamp. The fluorescent lamp converts 30% of the total electric energy into light energy but filament lamp converts only 10% electric energy into light energy.

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• ### This heating effect can be increased by use of ______.

more resistors

high voltage

heating element

galvanomater

• ### Nichrome wire, made from alloy of?

nickel and chlorine
nickel and chromium
nickel and aluminium
nitrogen and chromium
• ### Which lamp is filled with mercury vapor from inside and sealed with two sticking electrodes in each side?

None of above
In both lamp
Fluorescent lamp
Filament lamp
• ### Which powder is used in fluorescent lamp?

fluor powder
sodium powder
none of the above
Fluorescent powder
• ### The purpose of providing a choke in a tube light is ______.

to limit the excess current

to improve power factor

to increase the current supply

to limit resistivity of resistence

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