1. Why does the filament of a bulb glows when current flows through it?

When current flows through the filament of a bulb glows because it gets heated up and becomes red hot on flow of current through it.

2. What are some of the contribution of Thomas Alva Edison?

Thomas Alva Edison is credited for discovery of a number of devices including the photograph, the motion picture camera,and practical incandescent electric bulb. Edison also originated the concept and implementation of electric power generation and its distributions to homes, business centres and factories.

3. What are the factors that affect the amount of heat produced by flow of electric current through a wire?

The amount of heat produced by flow of electric current through a wire depends on material of wire length of the wire, thickness of the wire and the amount of current flow.

4. Define resistance.

When current flows through an electric wire, the latter tries to resist the current flow through it. This is called resistance.

5. The connecting wires used in electric circuits do not produce any heating effect .Why?

The connecting wires used in electric circuits do not produce any heating effect because they are made up of materials that have low resistance value .

6. Why is the filament wire of a bulb made very thin and given a helical shape?

Longer and thinner wires produced more heating than shorter and thick wires. This is the reason why the filament wire of a bulb made very thin given a helical shape to increase its length.

7. What are compact fluorescent lamps?

Compact fluorescent lamps are low energy bulbs and consumes less electricity. The longevity of a CFL is about 8 to 10 times more than an ordinary bulb.

8. Name some of the devices that are based on heating effects of current.

Electric heater, electric bulb, electric iron, geyser, immersion heater, electric hot plate etc are some of the devices that are based on heating effects of current.

9. What are the components of an electric fuse?

Each electric fuse consists of a metal wire fixed between two clamps.

10. Explain the working of a fuse wire.

The fuse wire melts quickly when current more than a specified value passes through it. The maximum current which was pass through a fuse without damaging it, is usually marked on its outer case. When current flowing through the fuse wire exceeds the marked current rating, the fuse wire melts and the fuse blows up. When a fuse connected in a circuit melts or blows up, it makes the circuit an open circuit and the flow of current stops thereafter.