Question

6. (a) Name a conductor, an insulator, a semiconductor, a ductile material and a brittle material.

(b) Why does a typical conductor show a relatively high electrical conductivity and a high ductility at room temperature? Comment on its electrical conductivity when it is heated.

(c) Derive the units of ductility and electrical conductivity.

Answer 1

Answer:

6(a) Names of all the required points are as given below:

Conductor: Copper, aluminium, silver, gold

Insulator: Glass, plastic, wood, rubber

Semiconductor: Silicon, Germanium

Ductile material: Copper, aluminium, steel

Brittle material: Cat iron, ceramics, concrete

(b) In case of conductors at room temperature they have free electrones and also electric current always consists of free electones beacuse of which electrones are free to move inside the conductoirs which make them to have good electric conductivity at room temperature

Ductility is the property of material by the virtue of which metarial can be deformed easily under the application of tensile force. It affects the thermal shock resistance of the material. If conductors are used at room temperature than they will show the higer ductility as at the moderate temperature ranges there is no loss of ductility due to embrittlement and the material can bear more thermal shocks at room temperature.

At high temperature what will be affect on electric conductivity of conductors:

As we discussed above that at romm temperature itself conductors have free electrons whioch improves the thermal conductivity of conductors but as the temperature is increased or conductors are heated, thermal velocity of the electones increases because of which electons collison takes place and due to this resistance increases and electic conductivity decreases. So at high temperatures, for conductors, electric conductivity decreases.

(c)

• Unit of ductility:

Ductility is the property of material by the virtue of which metarial can be deformed easily under the application of tensile force. Due to ductility material can witstand the plastic deformation without the rupture or failure and ductility is a dimensionless quantity.

It is generally defined as percentage elongation and can be written as % reduction in length

is final length after the fracture or rupture

is initial or gauge length

Ductility can also be defined as the % reduction in area as

'

This is % elongatio in area

Where is final area of specimen after rupture

is the initial area

• Unit of electric Conductivity:

Electric conductivity is the ability of material to conduct electricity.

Unit of electric conductivity is Siemens per meter

Conductivity is inverse of resistivity and can be given as

ρ represents resistivity and the unit of resistivity is Ohm meter

Siemens can be written as

  

Unit for this is  

And is also known as siemens

So from equation 1 we can say that the unit of electric conductivity is Siemens meter