Question
Question: Why is a fuse used in an electric appliance? A) To earth the appliance B) To protect the applian...
Why is a fuse used in an electric appliance?
A) To earth the appliance
B) To protect the appliance and its cable
C) To change the efficiency of the appliance
D) To change the current rating of the appliance
Solution
A fuse is an inevitable part of almost all electric appliances available today. It is nothing but a metal wire, connected in electric circuits for reasons such as safety. This metal wire has certain properties and has the power to control the working of an electric appliance.
Complete answer:
A fuse is a metal wire or a metal strip, used in many electric appliances such as cameras, mobile phones, laptops and televisions. This metal wire or strip is usually made from zinc, copper, silver or aluminum. It is connected in electric circuits of these appliances to protect them from conditions like overflow of current. A fuse has low melting point and can easily detect high currents in electric circuits. Once a fuse detects over current flow in the circuit, it breaks and makes the circuit an open circuit, so that no more current flows through the circuit. By doing this, the fuse protects the components of electric appliances and spare them from further damage.
In real-time situations, current flowing through electric circuits need not be consistent always. Therefore, it is important to include a fuse in the circuit of an electric appliance in order to maintain its safety. The working principle of a fuse can be understood as a heating consequence of high current. When spontaneous high current flows through a circuit of an electric appliance, the fuse in the circuit gets heated and as a consequence, it melts and breaks. A fuse generally has low melting point and its breakage disconnects the circuit and stops the current flow in the circuit. In this way, the electric appliance is protected.
There are different types of fuses available in the market. There are AC types of fuses as well as DC types of fuses. Some of the fuses available today can also be rewired. One can select a fuse according to the nature of the electric appliance as well as necessary requirements. Fuses are generally sold by naming them according to the maximum current, it can withstand without breakage.
To conclude, a fuse is basically a sacrificial device, which operates to make a circuit an open circuit, thereby protecting electrical appliances and associated wires from damage. A fuse can easily be replaced or rewired depending upon the requirements.
Therefore, the correct answer is B.
Note:
Students might get confused with the first option, which says that a fuse is used to earth an electric appliance. This is wrong because the concept of earthing is completely different from the concept of a fuse. Even though both these concepts deal with protection of electric appliances, earthing refers to the connection of exposed parts of a circuit to the ground or the earth, in order to avoid shocks. Sometimes, earthing can trigger the fuse in a circuit.