Question

Draw a labelled diagram of the experiment explaining Ohm’s Law.

Answer 1

Hint: We know that Ohm's law states the relation between current flowing through a conductor and the potential difference applied across its ends. We will now verify this law by using a variable resistor or rheostat to vary the resistance for various reading voltmeters to read the potential difference across the rheostat and ammeter to measure current flowing in the circuit.

Complete step by step answer:
To verify Ohm’s Law, we need to arrange the components of the circuit as shown in the given figure.
  

Connect the voltmeter across the terminals of the rheostat. Connect the ammeter and the battery in series to the rheostat. When all the circuit is complete insert the key and slide the rheostat to check the deflections in ammeter and voltmeter. Now insert the key again and slide the rheostat to vary the resistance in the circuit. Now, measure the current flowing in the circuit and the potential difference across the resistor. Again repeat the same procedure by varying the rheostat further and measure the current and potential difference. Repeat the procedure minimum five times and note down the reading of current and potential difference. Note the readings of current under column I and potential difference under column V. Now calculate the value of V over I for each reading taken. Now, write these calculated readings under column R. You will notice that the readings in column R are not much deviated. The readings appear to be constant. Plot a graph of the relation.
This experiment therefore, states that current flowing through a conductor is directly proportional to the voltage across two points of the conductor.
Therefore,
$$I\propto V$$
Now, after introducing the constant of proportionality we get our equation for Ohm’s law
$$I={\displaystyle \frac{V}{R}}$$
Or, $$V=IR$$
Where,
V is in volts, V
I is in Amperes, A
And R is ohms, $$\mathrm{\Omega }$$
Therefore, we can say that Ohm’s Law is verified.

Additional Information:
If the graph of Voltage vs Current is drawn the slope of the graph will give us the resistance as shown in the figure.

Note:
Students must note that only if the displacement of a body has some component parallel to or anti parallel to the direction of the force applied on it, then only some non zero quantity of work is done by the force. If the force applied and the displacement of the body are in perpendicular directions, this would mean that the displacement has no component along or opposite to the direction of the force and in turn this would mean that the work done by the force is zero, even though the force on the body and its displacement are non zero.