Question

to study the dependence of current (I) flowing on the applied potential difference (v) across a resistor a student set up his apparatus as shown .he puts the sliding contact j .in the position A,Band C.one by one and notes the three readings of the voltmeter as Va,Vb,Vc,and that of the ammeter as IA,Ib,Ic.​

Answer 1

Answer:

Aim:

To study the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. Also, plot a graph between V and I.

Theory:

What is Ohm’s law?

In an electric circuit, the potential difference V across the metallic wire is directly proportional to the current flowing through the circuit with a constant temperature. This is known as Ohm’s law.

V∝I. ∴ V=IR.

What are the factors affecting resistance?

Following are the factors affecting resistance:

The nature of the resistor.

With an increase in length, the resistance also increases. So length also affects the resistance.

With an increase in the cross-sectional area, the resistance decreases. So cross-sectional area of the wire affects the resistance.

★Materials Required:

Following is the list of materials required for this experiment:

• A battery
• An insulated copper wire
• A key
• An ammeter
• A voltmeter
• A rheostat
• A resistor
• A piece of sandpaper
• Circuit Diagram
• Circuit diagram

★Procedure:

Arrange the devices as shown in the circuit diagram.

1. Connect the devices with the connecting wires keeping the key open.
2. The positive terminal of the battery should be connected to the positive terminal of the ammeter.
3. Before connecting the voltmeter in the circuit, check for +ve and -ve terminals.
4. Check for ammeter and voltmeter reading once the circuit is connected and also adjust the slider of rheostat after inserting the key.
5. For current I and voltmeter V, record three different readings using a slider.
6. Record the observations in the observation table.
7. Using the formula R=V/I, calculate the resistance.
8. To plot the graph between V and I, take V on the x-axis and I on the y-axis.
9. For pure metals, resistance increases with an increase in temperature.