Correct Answer - Option 1 :
Resistance decreases with decrease in length of the wire
The correct answer is option 1) i.e. Resistance decreases with decrease in length of the wire
CONCEPT:
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Resistance: The hindrance to the flow of current offered by a material is called electrical resistance.
- The SI unit of electrical resistance is the ohm (Ω)
The resistance of a conducting wire is given by the equation:
\(R = \rho\frac{l}{A}\)
Where R is the resistance, l is the length of the wire and A is the cross-sectional area of the material.
EXPLANATION:
R ∝ l
- Therefore, resistance decreases with a decrease in the length of the wire.
\(R \propto \frac{1}{A}\)
- The thickness of the wire is a measure of the cross-sectional area. Hence, the increasing thickness increases the cross-sectional area of the material.
- Therefore, resistance increases with a decrease in the thickness of the material.
- On increasing the temperature of the wire, the kinetic energy of the electrons in the material increases and they collide vigorously with each other.
- Each collision uses some of the energy of electrons and thus electron flow slows down. This increases resistance. However, this is only true for metals.
- In insulators and semiconductors, the number of free electrons increases with an increase in temperature. Thus, resistance decreases.