Here is a quick glimpse over the Factors on which the resistance of a conductor depends. Exclusive for students of Class 10 CBSE, who are studying the lesson "Electricity" Based on the concept given in the presentation, numerical questions have also been given with the solutions for practice and reference. You can check out my other Presentations in my profile

1. Factors on which the resistance of a conductor depends
Presentation compiled by:
Dhananjay M.R

2. Resistance:
The electrical resistance
of an object is a measure
of its opposition to the
flow of electric current
Resistivity:
Resistivity is the
characteristic property of
the material by which
it resists the amount of
current through it.
Both the
resistance
and
resistivity of
a material
vary with
temperature.

3. Resistivity
• Resistivity is the characteristic property of the material by
which it resists the amount of current through it
• It depends upon the nature of the material and materials
and physical conditions like temperature
• SI Unit: Ohm-meter
• It is denoted by ρ (Rho).

4. Resistance
•The electrical resistance of circuit is a
measure of its opposition to the flow of
electric current.
•SI Unit: Ohm (Ω )
•It is denoted by R

5. Conductors, Alloys & Insulators
• Conductors refer to certain kind of materials or objects that
permits the flow of electric current (charge) in one or more than
one direction. EG. Metals, Electrolytes etc.
• Insulators refer to the material which doesn't allow electricity and
to pass from it. EG. Pin insulators, Suspension insulators, wood,
rubber etc.
• An alloy is a substance which is formed when two or more metals
are combined. They can also be formed when metals are
combined with other elements. EG. brass, pewter, phosphor
bronze, amalgam, and steel.

7. Properties of
Resistance in
a Conductor
The resistance of a conductor depends on
varies properties, such as:
• The Length of the conductor
• The area of its cross-section
• The nature of its material
Accurate measurements have proven that the
resistance of a uniform metallic conductor is
directly proportional to its length and
inversely proportional to the area of its cross-
section.

8. Properties of
Resistance in
a Conductor
The resistance of a conductor depends on
varies properties, such as:
• The Length of the conductor
• The area of its cross-section
• The nature of its material
Accurate measurements have proven that the
resistance of a uniform metallic conductor is
directly proportional to its length(l) and
inversely proportional to the area of its cross-
section(A).
R ∝ l(Length)
R ∝ 1/A(Area of Cross-section)

9. Properties of
Resistance in
a Conductor
The resistance of a conductor depends on
varies properties, such as:
• The Length of the conductor
• The area of its cross-section
• The nature of its material
Accurate measurements have proven that the
resistance of a uniform metallic conductor is
directly proportional to its length(l) and
inversely proportional to the area of its cross-
section(A).
R ∝ l(Length)
R ∝ 1/A(Area of Cross-section)
R = ρ x l/A, ρ(rho)*
ρ = constant of proportionality

10. Sums

11. Q1 . How much current will an electric bulb
draw from a 220 V source, if the resistance of
the bulb filament is 1200 Ω?
Solution:
We are given,
V = 220 V
R = 1200 Ω
We need to find current
We know that I=V/R, We get:
I = 220 V/1200 Ω
I= 0.18 A

12. Q2 . How much current will an electric heater
coil draw from a 220 V source, if the
resistance of the heater coil is 100 Ω?
Solution:
We are given ,
V = 220 V, R = 100 Ω.
We need to find current
We know that I=V/R, We get:
I = 220 V/100 Ω
I = 2.2 A.
• Note the difference of current drawn by an electric bulb and
electric heater from the same 220 V source!

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