Advertisements
Advertisements
प्रश्न
How will the resistance of a wire be affected if its
- length is doubled, and
- radius is also doubled ?
Give justification for your answer.
Advertisements
उत्तर
R `=(rho"l")/"A"`
Where, `rho` = electrical resistivity
l = length of the conductor
A = cross-sectional area of the conductor
Hence if the length is double then
⇒ `"R"_1=rho((2"l"))/"A"`
`therefore "R"_1 = 2("R")`
So, if the length of the resistance gets doubled then resistance also gets doubled.
Now when the radius is double then
⇒ `"R"_2 = (rho"l")/"A"`
⇒`"R"_2 = (rhol)/(pi(2"r")^2`
`therefore "R"_2 = 1/4("R")`
So if the radius gets doubled then resistance will be `(1/4)^"th"` of initial resistance.
APPEARS IN
संबंधित प्रश्न
Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be:
A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10−8Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?
List the factors on which the resistance of a conductor in the shape of a wire depends.
Distinguish between good conductors, resistors and insulators. Name two good conductors, two resistance and two insulators.
What is meant by the "resistance of a conductor" ? Write the relation between resistance, potential difference and current.
Which has more resistance:
a long piece of nichrome wire or a short one?
Which has more resistance:
a thick piece of nichrome wire or a thin piece?
How does the resistance of a conductor depend on:
length of the conductor?
What would be the effect on the resistance of a metal wire of:
increasing its temperature?
Plastic insulation surrounds a wire having diameter d and length l as shown above. A decrease in the resistance of the wire would be produced by an increase in the ______.
