Ohm’s Law Welcome to the Tribute to Scientists Association. Presenting, Sir Georg Simon Ohm. Let us study his law. German physicist Georg Simon Ohm stated that the electric current flowing through a metallic wire is directly proportional to the potential difference across its ends, provided its temperature remains the same. This law is called Ohm’s law. Let us verify the law with an activity. Nichrome wire of 0.5 m, milliammeter, voltmeter, switch and a cell of 1.5 volts. Connect the cell with. The nichrome wire. Milliammeter. Voltmeter. What will happen now? Keep watching. When one cell is connected. The current is 120 mA. The potential difference is 0.3 V. This is amazing. Can I use your phone, please? I need a cell of 1.5 V, please. Please make it quick. In the meantime, let’s have some coffee. After sometime. Now, we have connected two cells. When two cells are connected. The current is 200 mA. The potential difference is 0.5 V. After sometime. Three cells connected. When three cells are connected. The current is 300 mA. The potential difference is 0.75 V. This was amazing. Thank you for inviting me. Let’s see the results of his activity. When number of cells increases. The value of current increases. The value of voltage increases. The ratio of voltage to current is constant in all the readings, that is, 2.5 V per ampere. Conculsion: Voltage is directly proportional to current. Ohm’s law verified. The V-I graph is a straight line passing through the origin. Hence, V is directly proportional to I or V upon I is constant. This constant is R. R is the resistance of the metallic wire at its given temperature. Hence, V upon I is equal to R or V is equal to IR. Thank you for being with us today. The End.