Q23 of 35 Page 93

How does use of a fuse wire protect electrical appliances?

An electric fuse is wire which is made of a material of high resistance and low melting point. Using an electric fuse prevents the flow of unduly high electric current and protects the appliances from the damage. Due to Joule heating, the fuse melts to break the electric circuit.


More from this chapter

All 35 →
21

Should the resistance of an ammeter be low or high? Give reason.

 22

Draw a circuit diagram of an electric circuit containing a cell, a key, an ammeter, a resistor of 2 Ω in series with a combination of two resistors (4 Ω each) in parallel and a voltmeter across the parallel combination. Will the potential difference across the 2 Ω resistor be the same as that across the parallel combination of 4Ω resistors? Give reason.

 24

What is electrical resistivity? In a series electrical circuit comprising a resistor made up of a metallic wire, the ammeter reads 5 A. The reading of the ammeter decreases to half when the

length of the wire is doubled. Why?

 25

What is the commercial unit of electrical energy? Represent it in terms of joules.