6(i) – 6(iv) are based on the information given below. Study this
information related to (4) and answer the questions that follow.
Resistance of a conductor depends on the length, area of cross-section and
nature of the material of the conductor. When a conductor is stretched
(increased in its length) then its area of cross section decreases accordingly
but the volume (i.e. area x length) of the conductor remains same-
(i) Define resistivity of a conductor.
(ii) What is the S.I. unit of resistivity?
(iii) Write one difference between resistance and resistivity.
(iv) If the resistance R of a wire of length is halved and area of cross section A
is doubled, what will be the new resistance?
Answers
Answer:
(i) Resistivity is defined as the electrical resistance of a conductor of unit cross-sectional area and unit length.
(ii) ohm⋅metre (Ω⋅m).
(iii) the key differences between resistance and resistivity are:-
1) The resistance is the property of the material which obstructs the flow of current, whereas the resistivity gives the resistance of the material which has fixed dimension.
2)The resistance is the ratio of the length and cross-section area of the conductor, whereas the resistivity of the material is the ratio of the product of the resistance and area to the length of the conductor.
3) The resistance is represented by the symbol R whereas the resistivity is represented by the symbol ρ.
4)The SI unit of the resistance is ohm, and the SI unit of resistivity is ohm-meter.
5)The resistance of the material depends on the length, cross-section and area of conductor whereas the resistivity depends on the nature and temperature of the material.
(iv) answer is in image
