What is electrical resistivity of a material? What is its unit? Describe an experiment to study the factors on which the resistance of conducting wire depends.
NCERT Class X
Science - Exemplar Problems
Chapter_Electricity
Answers
The experiment involves setting up an circuit that consists of a battery resistance an rheostat an voltmeter and ammeter. On variable resistance the reading of voltmeter and ammeter should remain constant that is equal to Resistance.
R = V/I which remains constant
Hence resistance depends on area and length of the conductor
Answer:
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Explanation:
Ans. The inherent property of a conductor because of which it resists the flow of electric
current is called resistivity. Resistivity for a particular material is unique,
(Ohm metre),
The SI unit of resistivity is Experiment to study the factors on which resistance of conducting wire depends:
• Take an ammeter, electric cell, plug key, nichrome wire and wires of different
materials
Make the circuit as shown in figure.
• Start the experiment with nichrome wire. Attach it in the circuit and take ammeter
reading
• Change the length of nichrome wire and take ammeter reading
• Change the thickness of nichrome wire and take ammeter reading
After above steps, use copper wire for the experiment. Attach a copper wire in the
circuit and take ammeter reading.
Change the length of copper wire and take ammeter reading,
Change the thickness of copper wire and take ammeter reading
• Repeat above steps with wires of different materials
Observations:
• It is seen that resistance depends on material of conductor.
Resistance depends on length of conductor.
• • Resistance depends on area of cross-section.