Apps-On-Physics/C3/Ohm's-Law-and-its-Applications/English-timed

Time	Narration
00:01	Welcome to the Spoken Tutorial on Ohm's law and its applications.
00:07	At the end of this tutorial you will be able to:
00:10	Verify Ohm’s Law.
00:12	Solve a numerical based on Ohm’s law.
00:16	Draw a graph to find the relation between voltage and current.
00:21	Solve a numerical based on series and parallel combination and
00:26	Calculate the value of current in the circuit.
00:31	Here I am using, Ubuntu Linux OS version 16.04
00:37	Firefox Web Browser version 62.0.3
00:42	To follow this tutorial, learner should be familiar with Apps on Physics.
00:48	For the pre-requisite tutorials please visit this site.
00:52	In this tutorial we will use Ohm’s Law and Combinations of Resistors Apps.
01:00	I have already downloaded Apps on Physics to my Downloads folder.
01:05	Right click on the ohmslaw_en.htm file.
01:10	Select Open With Firefox Web Browser option.
01:14	Ohm’s Law App opens in the browser.
01:19	The App shows a simple circuit containing one resistor.
01:24	Green panel has two yellow buttons for resistance and two blue buttons for voltage.
01:31	Click on Increase resistance button.
01:34	Notice that as we increase the resistance, ammeter shows decrease in the current.
01:41	This increase in resistance, decrease the current in the circuit.
01:46	The value of current decreased from 0.03 Ampere to 0.02 Ampere.
01:54	Click on the Increase voltage button.
01:58	Change in voltage is shown by the voltmeter connected in the circuit.
02:04	The maximum voltage of a circuit is 10 V.
02:09	Click on the Maximal voltage drop down.
02:12	Here we can see various ranges for the maximum voltage.
02:17	We can vary the voltage between these measuring ranges.
02:02	From the Maximal voltage drop down select 100 V.
02:27	Note that we can vary voltage between 1 to 100 V.
02:32	Click on the Increase voltage button continuously.
02:37	Notice that the voltage increases in the steps of 10 V.
02:42	When voltage crosses the maximum voltage range, circuit prompts Maximum exceeded.
02:49	Note that the Maximal amperage range is 100 mA.
02:54	So when the current in the circuit exceeds 100 miliAmp, circuit shows Maximum exceeded below the ammeter.
03:03	Let us change the Maximal amperage to 300 miliAmp.
03:08	Click on the Maximal amperage drop down.
03:11	Select 300 milliampere from the drop down.
03:15	Now let us calculate current in the circuit using Ohm’s law.
03:21	Scroll down the screen.
03:24	Here the App has stated the Ohm’s law.
03:28	Press F5 key on the keyboard to restart the App.
03:33	Let us solve this numerical.
03:36	Please pause the video and read the numerical.
03:41	First let us change the values of the parameters according to the numerical.
03:47	For that we have to convert the value of current to milliampere.
03:52	1 Ampere = 1000 miliAmpere
03:56	So, 0.03 Ampere = 30 miliAmpere
04:02	Next from the Maximal amperage drop down select 30 miliAmpere.
04:08	Default value of resistance is 200 ohms.
04:12	Let us calculate the value of voltage using the formula.
04:17	Substitute the values of current and resistance into the formula.
04:22	The calculated value of voltage is 6 V.
04:26	It is same as the value shown in the App.
04:30	Let us find the relation between voltage, current and resistance using a graph.
04:37	Press F5 key on the keyboard to restart the App.
04:42	From the Maximal voltage drop down select 100 volts.
04:48	From the Maximal amperage drop down select 1 Ampere.
04:52	Next click on Increase voltage button.
04:56	We can click on Increase voltage button to get the value of voltage in steps of 10 Volts.
05:03	Observe the change in the current as we change the voltage.
05:08	Now make a tabular column to note the values of voltage and current.
05:14	Go to the interface and check the value of current for 10 Volts.
05:20	The value is 0.05 Ampere.
05:24	Again click on Increase voltage button.
05:58	Note the value of current at 20 Volts in the tabular column.
05:33	Similarly I have noted the values of current in the table.
05:38	Here I have drawn the graph of current v/s voltage.
05:43	The graph is linear.
05:46	Voltage is directly proportional to current in a metallic conductor.
05:50	Here straight line shows the constant of proportionality, that is resistance. This verifies the Ohm’s law.
05:59	As an assignment, Change the Maximal voltage to 1000 V and Maximal amperage to 10 ampere.
06:08	Make a tabular column to note the values of voltage and current.
06:14	Change the voltage in the steps of 100 Volt.
06:18	Draw the graph and explain your observation.
06:22	Let us open the next App.
06:25	Open Combinations of Resistor App in a similar way as we opened Ohm’s Law App.
06:32	Combinations of Resistor App opens in the browser.
06:37	Here the App shows a simple circuit. It consists of a resistance and a battery.
06:46	Here we can see Voltage of the battery and Resistance text boxes.
05:52	We can change the values of voltage and resistance using these text boxes.
06:58	The maximum limit of Voltage of the battery is 1000 Volts.
07:03	The maximum limit of Resistance is 1000 ohms.
07:08	Click on Reset button to get the default values.
07:12	In this App we will learn about series and parallel combinations of resistances.
07:19	To add resistor in series click on Add resistor in series button.
07:25	Notice that the added resistor is in series with the original resistor.
07:31	It also has the same resistance value, 100 ohms.
07:36	We can change the value of the selected resistor in the Resistance text-box.
07:42	Change the value of Resistance to 50 ohms.
07:46	Here we can see the values of Voltage, Amperage and Resistance of the circuit.
07:53	At the bottom of the green panel there are two check-boxes for meters. Voltage and Amperage.
08:01	Click on the Voltage check box.
08:04	Observe that voltmeter is connected to the resistor which is selected by default.
08:11	Uncheck the Voltage check-box.
08:14	Click on other resistance in the circuit.
08:18	Again click on Voltage check-box.
08:22	Now the voltmeter is connected to the selected resistance.
08:27	Next click on Amperage check-box to see the value of current.
08:33	Note that ammeter is connected in series and voltmeter is connected in parallel.
08:40	Ammeter is a device of lower resistance value.
08:44	So it allows current to pass through it.
08:48	Hence it is connected in series.
08:52	On the other hand voltmeter is a device with high resistance.
08:57	If we connect it in series it will resist the flow of current in the circuit.
09:03	That is why it is connected in parallel to allow the current to pass through it.
09:09	Click on the Reset button.
09:12	Change the value of Resistance to 250 ohms.
09:16	Next click on Add resistor in series to add 2 more resistances.
09:23	Remember that we can only use three resistors in series.
09:28	Click and move the cursor on the resistors in the circuit. It shows 750 ohms.
09:36	This is the value of equivalent resistances in series.
09:41	Now let us know how to calculate the series and parallel resistances.
09:47	Next click on Add resistor in parallel button.
09:52	Note that a resistor of 250 ohms is added parallelly to the series resistances.
09:59	Again click and move the cursor over the resistances.
10:04	Here the value of equivalent resistance is 188 ohms.
10:10	Let us see how the App has calculated the value of equivalent resistance.
10:16	The three resistance are in series combination, so we will add these resistances.
10:24	This gives the value as 750 ohms.
10:28	This 750 ohms resistance is connected in parallel with a 250 ohms resistance.
10:36	To calculate parallel combination we use this formula.
10:41	We will substitute the value of R1 as 750 ohms and R2 as 250 ohms.
10:49	I have solved the equation and got the value as 187.5 ohms.
10:56	Note that the calculated value is comparable to the observed value.
11:02	Let us solve a numerical based on series combination.
11:07	Please pause the video and read the numerical.
11:11	Now according to the numerical let us form a circuit on the interface.
11:17	Click on the Reset button.
11:20	Change the Voltage of the battery to 20 Volts and press Enter.
11:25	Enter 110 ohms in Resistance text-box and press Enter.
11:32	Click on Add resistor in series button.
11:36	Change the value of selected resistor to 50 ohms.
11:41	Similarly add the third resistor and change the value to 180 ohms.
11:47	As the resistors are connected in series we will add the resistances.
11:53	So, the calculated value of resistance is 340 ohms.
11:59	Next to calculate the current in the circuit we will use the ohm’s law.
12:05	Rearrange the equation so as to calculate the value of current.
12:10	Substitute the value of voltage and equivalent resistance.
12:15	Click on the Amperage check-box to see the value of current. Observe that the values are same.
12:24	As an assignment solve this numerical.
12:29	Let us summarize
12:31	Using these Apps we have, Verified Ohm’s Law.
12:36	Solved a numerical based on Ohm’s Law.
12:40	Drawn a graph to find the relation between voltage and current.
12:45	Solved a numerical based on series and parallel combination.
12:51	Calculated the value of current in the circuit.
12:55	These Apps were created by Walter-Fendt and his team.
13:00	The video at the following link summarises the Spoken Tutorial project. Please download and watch it.
12:08	TheSpoken Tutorial Projectteam, conducts workshops and gives certificates. For more details, please write to us.
13:18	Please post your timed queries in this forum.
13:22	The Spoken Tutorial Project is funded by MHRD, Government of India.
13:28	This is Himanshi Karwanje from IIT-Bombay. Thank you for joining.

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