i. Longer line in the symbol for a cell represents its positive terminal.
ii. The combination of two or more cells is called a battery.
iii. When current is switched ‘on’ in a room heater, it produces heat.
iv. The safety device based on the heating effect of electric current is called a fuse.
i. To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. False
ii. When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. True
iii. An electromagnet does not attract a piece of iron. False
iv. An electric bell has an electromagnet. True
Ans. Electric current is flow of electrons.
Ans. Light bulb gets hot due to heating effect of the electric current.
Ans. Hans Christian Oersted discovered magnetic effect of current.
Ans. In the bulb there is a thin wire, called the filament, which glows and gives off light when an electric current passes through it.
Ans. Many devices such as torches, transistors, toys, TV remote controls, use batteries.
Ans. Nichrome wire is used in electric heater because it has a high melting temperature.
Ans. In the bulb there is a thin wire, called the filament, which glows when an electric current passes through it.
Ans. Yes, if a large current passes through a wire, the wire may become so hot that it may even melt and break.
Ans. The wire gets hot when an electric current passes through it. This is the heating effect of the electric current.
Ans. The credit for the invention of the electric bulb is usually given to Thomas Alva Edison, though others before him had worked on it.
Ans. Electrical appliances, such as immersion heaters, hotplates, irons, geysers, electric kettles, hair dryers uses of heating effect of electric current.
Ans. In the symbol of the electric cell, the longer line represents the positive terminal and the thicker, shorter line represents the negative terminal.
Ans. The two effects of electric current are:
i. Heating effect of electric current
ii. Magnetic effect of the electric current
Ans. Fuse wires are not used in circuit containing electric cell because the amount of current follow is low and if the circuit breaks there is no risk of fire.
Ans. The electric circuit provides a closed path for electricity to pass between the two terminals of the electric cell. The bulb glows only when current flows through the circuit.
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