General Knowledge - Basic General Knowledge - Discussion

49. 

For safety, the fuse wire used in the mains for household supply of electricity must be made of metal having

[A]. low melting point
[B]. high resistance
[C]. high melting point
[D]. low specific heat

Answer: Option A

Explanation:

No answer description available for this question.

Vishal Devgan said: (Dec 17, 2010)  
The melting point of a solid is the temperature at which the vapor pressure of the solid and the liquid are equal. At the melting point the solid and liquid phase exist in equilibrium. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point. Because of the ability of some substances to supercool, the freezing point is not considered to be a characteristic property of a substance. When the "characteristic freezing point" of a substance is determined, in fact the actual methodology is almost always "the principle of observing the disappearance rather than the formation of ice", that is, the melting point.

Nivedha said: (Dec 21, 2010)  
Oh yep. But I thought high resistance. Is it correct?

Justin C Das said: (Dec 26, 2010)  
The fuse wire is used on the basis on the Joules law of heating.

The law says that when the electric current is allowed to pass trough a conductor, the conductor heats up and is proportional to the square of current.This is because practical conductors have definite resistance(normally it is small).

The heat produced= Isq*R*T

The main object of using fuse wire in electric circuit is to provide protection against short circuit or overload current. This means it protects the circuit from huge amount of current flow as it cause the damage to the circuit.
The fuse wire select such a way that it burns and break the circuit when large current passes. For this purpose the material used as fuse wire should have high resistance and low melting point.Due to high resistance the wire heats up quickly, when huge current flows. The temperature around the fuse wire rapidly rises, when it reaches the melting point of the material it burns and protects the circuits.

High resistance and low melting point are responsible to the quick response of the fuse wire towards the current.

The common material used as fuse wire is an alloy of tin and lead.

Bharath said: (Jul 16, 2011)  
A fuse wire should always have a high resistance and low melting point.

High resistance to heat up soon and low melying point to melt away due to the heat produced by high resistance so that the circuit is not damaged.

Rajehwar Joshi said: (Aug 17, 2011)  
A fusible alloy is a metal alloy capable of being easily fused, i.e. easily meltable, at relatively low temperatures. Fusible alloys are commonly, not necessarily, eutectic alloys.

Sometimes the term "fusible alloy" is used to describe alloys with a melting point below 150 degree C (302 degree F). Fusible alloys in this sense are used for solder.

Sanjeev said: (Aug 24, 2011)  
So both A and B are right

Sangamesh said: (Jan 20, 2012)  
Basic idea is to protect household devices. So that only that fuse will spoil due to high current rest house devices get protected. Because fuse cost is less. It can be replaced as it's cost is low compared to costly house hold circuit devices.

Yashfeen said: (Dec 9, 2012)  
The fuse wire must be of low melting point. When excess current is flowed the fuse wire melt up and electrical appliances are saved.

Ritesh Kumar said: (Jan 20, 2013)  
If the melting point of fuse wire will be more, then it will take more time to disconnect the supply system at the time of fault occurred and the electronic components will be get damaged.

So melting point must be low for fuse wire.

Malli said: (Apr 23, 2013)  
Because the wire has to melt when sudden variation in the current/voltage, otherwise it may damage electric instruments inside the house. By melting it avoid a damage to the other instruments hence need to have low melting point fuse wire.

Sreehari said: (Jul 19, 2013)  
Low melting point is the answer. Because fuse wire should be broken when an excess current flows through it. (according to H=I^2*R*T ).

Kritika said: (Nov 23, 2013)  
Yes low melting point is the answer so as to prevent a short circuit from materializing because if a high current passes through it, it would melt and thus break the circuit.

Rajesh said: (Dec 10, 2013)  
A fuse wire must have high resistance and low melting point.

Sajin Vineeth said: (Apr 5, 2014)  
Tinned copper and other low melting wire used in fuse is it right ?

M.Rajesh said: (Apr 9, 2014)  
Metal wire must having high melting point in fuses.

Lysiya Merlin S said: (Jun 19, 2014)  
The concept of fuse can be better understood by knowing the term called threshold. Its defines the maximum and minimum usable voltage levels of any circuit. Once the employed voltage in a circuit exceeds the predefined threshold value mentioned by the manufacturer it may lead to circuit malfunctioning thereby it arises errors or defects at the output due to burning of wires in the internal circuitry, also it may cause damage to the circuit. In order to avoid this problem the concept of fuse wire is used.

At the times of any part of the circuit facing higher voltages than the specified threshold voltage, the fuse wire receives the exceeded voltage and get burnt, which protects other internal circuitry wires from getting damaged. This is possible only when the fuse wire is having lower melting and higher resistance value as heat produced is proportional to current and resistance. Usually high resistance coils have low melting point.

Rakesh Kumar said: (Sep 25, 2014)  
Fuse has low melting point of fuse wire which will be burn at high current through wire.

Bibhudatta Nayak said: (Oct 3, 2014)  
Fuse high specific resistance and low melting point.

Iam Genius said: (Feb 20, 2015)  
If a fuse has high resistance than it will also interfere with the working impedance of the circuit.

Let me say we have circuit with some impedance and a high resistance fuse connected in series. Now if fault occurs then it would be limited by the high resistance of the fuse. So there is no need for the fuse to melt.

See all I want to say is how can you use a high resistance material to protect something from over current.

Rajesh said: (Mar 14, 2015)  
Fuse (lead+tin) has high specific resistance than copper. But fuse resistance is lesser than load.

Aaishu said: (Mar 19, 2015)  
Yes, lead is used in fuse because of low melting point & high resistance.

Prosenjit Halder said: (Jan 23, 2016)  
A fuse wire always should have high resistance and low melting point.

Samayara said: (Apr 28, 2016)  
I agree @Prosenjit Halder.

The high resistance is correct to tha concept of resistance and current.

Subhra said: (Jul 12, 2016)  
The material should have low melting point and low resistance.

Low resistance because if there is low are then there will be large current and heat produced in fuse material is more dependent on current (I) than resistance.

Subhra said: (Jul 12, 2016)  
Example. A 50 ohm resistance is connected accros a 100 volt supply, then heat will be is 200 joule in 1 sec. Now the resistance of 20 ohm is connected of same material accros the supply. Now heat will be 500 joule in 1 sec.

Abhi said: (Aug 25, 2016)  
Fuse is connected in series with load so we consider current passing though it.

Imtxn said: (Sep 21, 2016)  
The discussion has been about fuse impedances & melting point. Can we discuss factors affecting fuse operating points?

Anmol (Mit Professor) said: (Nov 24, 2016)  
Fuse is a low resistance and melting point sacrificial device.

Sobia said: (Mar 13, 2017)  
The piece of wire which melts due to exceed of current is called __________.

Bulb, Rubber, Fuse, circuit.

Answer this.

Pankaj said: (Jun 10, 2017)  
Those who are saying fuse wire have high resistance! I would like to ask them if it is so then according to them it must be low conductivity!

But as far as I know fuse wire must have high conductivity. You guys can decided (G=1/R).

Sk Jahedul Islam said: (Oct 9, 2017)  
As fuse wire alawys connect series with load.

It's a protective device.
H=I2RT.
From this equation, if we increase the value of heat by increasing ckt current or resistance.
If it's low resistance, that means we going to allow high current and it's damage our device.
So better if it's high resistance then the value of H increase and it's melt and protects the device.
Fuse material should low melting point , high resistance and high specific resistance(as length and cross-section of fuse material constant)

Vigesh said: (Feb 27, 2018)  
The melting point of the fuse material should be low because the material should act faster to ihe increase in temperature so as to break the circuit (open circuit).

Ketan said: (Aug 24, 2018)  
What is short circuit? Please explain briefly in technical.

Debashisd said: (Apr 7, 2022)  
Fuse wire is a wire of high resistance and low melting point.

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