(a) Define resistivity. Write an expression for the resistivity of a substance. Give the meaning of each symbol which occurs in it.
(b) State the SI unit of resistivity.
(c) Distinguish between resistance and resistivity.
(d) Name two factors on which the resistivity of a substance depends and two factors on which it does not depend.
(e) The resistance of a metal wire for length 1 m is 26ohm at 20o C, If the diameter of the wire is 0.3 mm, what will be the resistivity of the metal at that temperature?
(a) Define resistivity. Write an expression for the resistivity of a substance. Give the meaning of each symbol which occurs in it.
(b) State the SI unit of resistivity.
(c) Distinguish between resistance and resistivity.
(d) Name two factors on which the resistivity of a substance depends and two factors on which it does not depend.
(e) The resistance of a metal wire for length 1 m is 26ohm at 20o C, If the diameter of the wire is 0.3 mm, what will be the resistivity of the metal at that temperature?
a) Resistivity is the measure of a material's ability to oppose the flow of current. Resistivity of a conductor is a property of the material of the conductor.
Following is the equation relating resistivity (
) and resistance (R ) of the conductor of Length (L) and area (A)
(b)SI unit of Resistivity is 
c)
Resistance Resistivity
Resistance is the obstruction offered in the flow of current by the wire. It is the tendency of a substance to offer obstruction in the flow of current per unit length and per unit area. It depends on - material of the wire
- temperature of wire
- area of cross-section
- length of wire
It depends material of the wire.
(It does not depend on length and area of cross-section as both of them are taken as one unit given in definition.)
d)
The resistivity of a material depends on its nature and the temperature of the conductor, but not on its shape and size. A good conductor has less resistivity, whereas a bad conductor or insulator has high resistivity. The resistivity of semi-conductors lies between that of conductors and insulators. The resistivity of a metallic conductor increases with an increase in its temperature, whereas the resistivity of a semi-conductor decreases with an increase in its temperature.
e)
Given Data:
Resistance of wire, =26ohm
Radius of wire=half of the diameter=1.5×10−4m2
Cross sectional area of wire, =π(1.5×10−4)2
Length of the wire=1m
Resistivity=RAL
Resistivity=26×π×(1.5×10−4)21m=1.83×10−6ohm−m
a) Resistivity is the measure of a material's ability to oppose the flow of current. Resistivity of a conductor is a property of the material of the conductor.
Following is the equation relating resistivity () and resistance (R ) of the conductor of Length (L) and area (A)
(b)SI unit of Resistivity is
c)
Resistance Resistivity
| Resistance is the obstruction offered in the flow of current by the wire. | It is the tendency of a substance to offer obstruction in the flow of current per unit length and per unit area. |
It depends on
| It depends material of the wire. (It does not depend on length and area of cross-section as both of them are taken as one unit given in definition.) |
d)
The resistivity of a material depends on its nature and the temperature of the conductor, but not on its shape and size. A good conductor has less resistivity, whereas a bad conductor or insulator has high resistivity. The resistivity of semi-conductors lies between that of conductors and insulators. The resistivity of a metallic conductor increases with an increase in its temperature, whereas the resistivity of a semi-conductor decreases with an increase in its temperature.
e)
Given Data:
Resistance of wire, =26ohm
Radius of wire=half of the diameter=1.5×10−4m2
Cross sectional area of wire, =π(1.5×10−4)2
Length of the wire=1m
Resistivity=RAL
Resistivity=26×π×(1.5×10−4)21m=1.83×10−6ohm−m
