Define resistance of a conductor. State the factors on which resistance of a conductor depends. Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.
Calculate the resistance of 50\ \text{cm}50 cm50, space, start text, c, m, end text length of wire of cross sectional area 0.01\ \text{mm}^20.01 mm
2
0, point, 01, space, start text, m, m, end text, squared and of resistivity 5\times10^{-8}\ \Omega\text m5×10
−8
Ωm5, times, 10, start superscript, minus, 8, end superscript, space, \Omega, start text, m, end text.
Answers
Explanation:
If I is the length of the conductor, A its area of the crosssection and R its total resistance then,
Where P is a constant of proportionality and is called the electrical resistivity of the material of the conductor. The SI unit of resistivity is Ohm meter.
Now, plug the key. Note the current in the ammeter. Now replace the wire by a thicker nichrome wire, of the same length. A thicker wire has a larger cross-sectional area. Again note down the current through the circuit. Instead of taking a nichrome wire, connect a copper wire in the circuit. Again note down the current.
The resistance of a conductor depends on the cross sectional area of the conductor, the length of the conductor, and its resistivity. Potentiometer are used often to change the resistance without changing the voltage source in an electric circuit
Answer: