Question 1

State difference between the wire used in the element of an electric heater and in a fuse wire.

Accepted Answer

The wire used in the element of electric heater has a high resistivity and have a high melting point, i.e. even at a high temperature element do not burn while fuse wire have a low melting point and high resistivity.

Question 2

Name two electric devices for each where (i) heating effect of current is used and (ii) magnetic effect of current is used.

Accepted Answer

The electric devices arei) Heating effect of current is used: Room heater and geyser.ii) Magnetic effect of current is used: Cranes and electric bell.

Question 3

What is/are the advantage of MCB over fuses?

Accepted Answer

MCB has several advantages over fuse:MCB is more sensitive to current than the fuse. It detects any abnormality in the current flow and automatically switches off the electrical circuit.In the case of MCB, the fault zone of the electrical circuit can be easily identified. Faulty circuit trips to the off position. On the other hand in case of the fuse, the complete fuse wire needs to be checked by opening fuse grip for confirming the fault zone.With MCB it is very simple to resume to the supply. You just need to push the knob of MCB back to on position. But in case of the fuse, the entire fuse wire needs to be replaced.MCB provides a better interface with the help of knob than a fuse. In case of the fuse, the compete for handle needs to be taken care out.Handling MCB is electrically safer than handling a fuse.MCB is reusable and hence has less maintenance and replacement cost. Whereas a fuse needs to be replaced whenever it goes faulty.

Question 4

Why are compact fluorescent lamps (CFLs) preferred over electric bulbs?

Accepted Answer

The electrical bulb uses more electric power and also wastes electrical energy in the form of heat. Whereas compact fluorescent lamps do not waste electrical energy in the form of heat and they also consume less energy.

Question 5

Write the function of a fuse.

Accepted Answer

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Question 6

Which of the following equipment does not work on principle of Joule's law?

Accepted Answer

The electric iron, electric heater and electric bulb are some of the familiar devices based on Joule&#8217;s Law, but electric fan is not based on Joule's Law. Thus option $D$ is correct.

Question 7

Name the device used these days in place of electric fuses in electrical circuits.

Accepted Answer

The name of device is Miniature Circuit Breaker (MCB).

Question 8

Why is a fuse wire made of a tin-lead alloy and not copper?

Accepted Answer

A fuse wire is made of tin alloy because it has low melting point, so that it may melt easily, whereas a copper wire cannot be used as a fuse wire because it has a high melting point due to which it will not melt easily when a short circuit takes place.

Question 9

State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?

Accepted Answer

Appliances based on heating effect of electric current are:1) Electric heater2) Electric iron3) Microwave oven4) Induction cookerFinely heated platinum wire is used in surgery rather than knife because melting point of platinum is $1768\ ^\circ C$ is very high so it does not get melted easily  when heated for cutting the tissues while doing surgery.

Question 10

What happens on connecting too many appliances at a time to a single socket?

Accepted Answer

Appliances are connected in parallel connection which leads to overall reduction in resistance in the circuit and more current flows through socket. Too many &#10;appliances in same socket means too much load connected parallely across&#10; same node. This will further  increase the current .  If the socket has no fuse, wiring of socket can burn as a result of this.

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Basics of Heating Effect of Electric Current

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Application of Heating Effect of Electrical Current

Heating Effect Of Electric Current