Name: Ohm’s Law & Introduction to Electric Resistance
Uploaded: 2019-07-19
Duration: 8 min 43 s
Description: In our attempt to establish a relationship between current and voltage, we will discover a new physical quantity in this video. Let's watch and learn.

Question

State Ohm's law. Suggest an activity to demonstrate ohm's law by drawing a circuit diagram. Draw a graph of

V

versus

I

.

Accepted Answer

Ohm's law states that current flowing through a conductor is directly proportional to potential difference applied across the ends of a conductor, provided physical conditions like temperature, pressure, etc. remains the same.

The circuit for demonstrating Ohm's law is illustrated in the figure given below:

Take four cells of $1.5 V$ each, one resistor made up of Nichrome of resistance $R$ ohm, an ammeter $A$ and a voltmeter $V$ . Connect these devices with insulated copper wire.
When one cell is connected to the circuit, the reading in the voltmeter is $1.5 V$ . This is because the potential difference of the cell is dropped across the resistance.

According to ohm's law $V = I \times R \Rightarrow I = \frac{1 .5}{R}$ .
When two cells are connected to the circuit, the reading in the voltmeter is $3 V$ . According to Ohm's law, $I = \frac{3}{R}$
Similarly, when three cells are connected to the circuit, the reading in the voltmeter is $4.5 V$ . According to Ohm's law,
$I = \frac{4.5}{R}$
A straight line is observed in the V- I graph.
Conclusion:
(a) $R$ is a constant
(b) The slope of the line is $R = \frac{V}{I}$ .

A graph of $V$ versus $I$ :

Sr. No. Number of cell used in circuit Current through the Nichrome wire $I$ (ampere) Potential Difference across wire $V$ (volt) $R = \frac{V}{I}$

$1$ $1$ $V$ $1.5$ $R$

$2$ $2$ $\frac{3}{R}$ $3$ $R$

$3$ $3$ $\frac{4.5}{R}$ $4.5$ $R$

$4$ $4$ $\frac{6}{R}$ $6$ $R$

State Ohm's law. Suggest an activity to demonstrate ohm's law by drawing a circuit diagram. Draw a graph of $V$ versus $I$ .

Important Questions on Electricity

Learn and Prepare for any exam you want !

State Ohm's law. Suggest an activity to demonstrate ohm's law by drawing a circuit diagram. Draw a graph of V versus I.

Important Questions on Electricity

Learn and Prepare for any exam you want !

State Ohm's law. Suggest an activity to demonstrate ohm's law by drawing a circuit diagram. Draw a graph of $V$ versus $I$ .