Question

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​

Answer 1

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 depe

answered Jun 29, 2018 by priya12 (-12,637 points)

Resistance of a uniform metallic conductor is directly proportional to the length (I) and inversely proportional to the area of cross-section.

i.e. R∝1

p is constant of proportionality and is known as electrical resistivity of the material S.I. unit of electrical resistivity of a material is: m. An experiment to study the factors on which the resistance of conducting wire depends can be demonstrated as follows:

1. Complete an electrical circuit which consists of a cell, an ammeter, a nichrome wire of length I.

2. Note down the reading from Ammeter.

3. Replace the nichrome wire with twice the length of earlier nichrome wire having same thickness.

4. Note down the ammeter reading in the given circuit.

5. Replace the nichrome wire with thicker nichrome wire having a large cross-section area. Note down the current through circuit.

6. Now, replace the nichrome wire with copper wire having same length and same area of cross-section.

7. Note down the value of current and observe the difference in the current in all the cases.

Following observations were noted:

1. The ammeter reading decreases to one-

half when the length of wire is doubled.

2. The ammeter reading is increased when thicker wire of same material and same length is used.

3. Change in ammeter reading is observed when copper wire is used. So, Resistance of conducting wire depends on various factors:

1. Length

2. Area of cross-section

3. Nature of material

Answer 2

Answer:

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

Observations:

• It is seen that resistance depends on material of conductor.

Resistance depends on length of conductor.

• • Resistance depends on area of cross-section.