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

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|| '''Time'''
|| '''Narration'''

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|| 00:01
||Welcome to the Spoken Tutorial on '''Ohm's law and its applications.'''

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|| 00:07
||At the end of this tutorial you will be able to:

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||00:10
|| Verify Ohm’s Law.

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||00:12
|| Solve a numerical based on Ohm’s law.

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||00:16
|| Draw a graph to find the relation between voltage and current.

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||00:21
|| Solve a numerical based on series and parallel combination and  

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||00:26
||Calculate the value of current in the circuit.

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|| 00:31
||Here I am using,

Ubuntu Linux OS version 16.04

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||00:37
||Firefox Web Browser version 62.0.3

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|| 00:42
||To follow this tutorial, learner should be familiar with '''Apps on Physics'''.

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||00:48
||For the pre-requisite tutorials please visit this site.


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|| 00:52
||In this tutorial we will use

'''Ohm’s Law''' and  '''Combinations of Resistors''' '''Apps'''.

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||01:00
||I have already downloaded '''Apps on Physics''' to my '''Downloads''' folder.

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||01:05
||Right click on the '''ohmslaw_en.htm''' file.

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||01:10
||Select '''Open With Firefox Web Browser '''option.

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||01:14
||'''Ohm’s Law App''' opens in the browser.

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|| 01:19
||The '''App '''shows a simple circuit containing one resistor.

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|| 01:24
||Green panel has two yellow buttons for resistance and two blue buttons for voltage.

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|| 01:31
||Click on '''Increase resistance '''button.

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|| 01:34
||Notice that as we increase the resistance, ammeter shows decrease in the current.

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||01:41
||This increase in resistance, decrease the current in the circuit.

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|| 01:46
||The value of current decreased from 0.03 Ampere to 0.02 Ampere.

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|| 01:54
||Click on the '''Increase voltage''' button.

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|| 01:58
||Change in voltage is shown by the voltmeter connected in the circuit.

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|| 02:04
||The maximum voltage of a circuit is 10 '''V'''.

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|| 02:09
||Click on the '''Maximal voltage''' drop down.

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||02:12
||Here we can see various ranges for the maximum voltage.

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||02:17
||We can vary the voltage between these measuring ranges.

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|| 02:02
||From the '''Maximal voltage''' drop down select 100 '''V'''.

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|| 02:27
||Note that we can vary voltage between 1 to 100 '''V'''.

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|| 02:32
||Click on the '''Increase voltage''' button continuously.

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||02:37
||Notice that the voltage increases in the steps of 10 '''V'''.

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|| 02:42
|| When voltage crosses the maximum voltage range, circuit prompts '''Maximum exceeded'''.

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|| 02:49
||Note that the''' Maximal amperage''' range is 100 mA.

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||02:54
||So when the current in the circuit exceeds 100 miliAmp, circuit shows '''Maximum exceeded''' below the ammeter.

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|| 03:03
||Let us change the '''Maximal amperage''' to 300 miliAmp.

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|| 03:08
||Click on the '''Maximal amperage''' drop down.

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||03:11
||Select 300 '''milliampere''' from the drop down.

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|| 03:15
||Now let us calculate current in the circuit using '''Ohm'''’s law.

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||03:21
||Scroll down the screen.

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|| 03:24
||Here the '''App''' has stated the '''Ohm'''’s law.


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||03:28
||Press '''F5''' key on the keyboard to restart the '''App'''.

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|| 03:33
||Let us solve this numerical.

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||03:36
||Please pause the video and read the numerical.

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||03:41
||First let us change the values of the parameters according to the numerical.

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|| 03:47
||For that we have to convert the value of current to milliampere.

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||03:52
||1 Ampere = 1000 miliAmpere

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||03:56
||So, 0.03 Ampere = 30 miliAmpere

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||04:02
||Next from the '''Maximal amperage''' drop down select 30 '''miliAmpere'''.

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||04:08
||Default value of resistance is 200 '''ohms'''. 

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||04:12
||Let us calculate the value of voltage using the formula.

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||04:17
||Substitute the values of current and resistance into the formula.

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||04:22
||The calculated value of voltage is 6 '''V'''.

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||04:26
||It is same as the value shown in the '''App.'''

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|| 04:30
||Let us find the relation between voltage, current and resistance using a graph.

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|| 04:37
||Press '''F5''' key on the keyboard to restart the '''App'''.

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|| 04:42
||From the '''Maximal voltage''' drop down select 100 '''volts.'''

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||04:48
||From the '''Maximal amperage''' drop down select 1 '''Ampere'''.

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|| 04:52
||Next click on ''' Increase voltage''' button.

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||04:56
||We can click on '''Increase voltage''' button to get the value of voltage in steps of 10 '''Volts'''. 

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||05:03
||Observe the change in the current as we change the voltage.

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|| 05:08
||Now make a tabular column to note the values of voltage and current.

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||05:14
||Go to the interface and check the value of current for 10 '''Volts'''.

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||05:20
||The value is 0.05 Ampere.

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|| 05:24
||Again click on''' Increase voltage''' button.

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|| 05:58
||Note the value of current at 20 '''Volts''' in the tabular column.

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|| 05:33
||Similarly I have noted the values of current in the table.

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|| 05:38
||Here I have drawn the graph of current v/s voltage.

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||05:43
||The graph is linear.

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||05:46
||Voltage is directly proportional to current in a metallic conductor.

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||05:50
||Here straight line shows the constant of proportionality, that is resistance.

This verifies the''' Ohm'''’s law.

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|| 05:59
||As an assignment, 

Change the '''Maximal voltage''' to 1000 '''V''' and''' Maximal amperage''' to 10 ampere.

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||06:08
||Make a tabular column to note the values of voltage and current.
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|| 06:14
||Change the voltage in the steps of 100 Volt.

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||06:18
||Draw the graph and explain your observation.

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|| 06:22
||Let us open the next '''App'''.

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||06:25
||Open '''Combinations of Resistor App''' in a similar way as we opened '''Ohm’s Law App'''.

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|| 06:32
||'''Combinations of Resistor App''' opens in the browser.

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|| 06:37
||Here the '''App''' shows a simple circuit. It consists of a resistance and a battery.

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|| 06:46
||Here we can see '''Voltage of the battery ''' and '''Resistance''' text boxes.

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||05:52
||We can change the values of voltage and resistance using these text boxes.

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|| 06:58
||The maximum limit of '''Voltage of the battery '''is 1000 '''Volts'''.

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|| 07:03
||The maximum limit of '''Resistance '''is 1000''' ohms.'''

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|| 07:08
||Click on '''Reset''' button to get the default values.

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||07:12
||In this '''App''' we will learn about series and parallel combinations of resistances.

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|| 07:19
||To add resistor in series click on '''Add resistor in series '''button.

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||07:25
||Notice that the added resistor is in series with the original resistor.

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||07:31
||It also has the same resistance value, 100 ohms.

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|| 07:36
||We can change the value of the selected resistor in the '''Resistance''' text-box.

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||07:42
||Change the value of '''Resistance''' to 50 ohms.

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|| 07:46
||Here we can see the values of''' Voltage''', '''Amperage''' and '''Resistance '''of the circuit.

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|| 07:53
||At the bottom of the green panel there are two check-boxes for meters.

'''Voltage''' and '''Amperage'''.

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|| 08:01
||Click on the '''Voltage''' check box.

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|| 08:04
||Observe that voltmeter is connected to the resistor which is selected by default.

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|| 08:11
||Uncheck the''' Voltage''' check-box.

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|| 08:14
||Click on other resistance in the circuit.
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|| 08:18
||Again click on '''Voltage''' check-box.

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|| 08:22
||Now the voltmeter is connected to the selected resistance.

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|| 08:27
||Next click on '''Amperage '''check-box to see the value of current.

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|| 08:33
||Note that ammeter is connected in series and voltmeter is connected in parallel.

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|| 08:40
||Ammeter is a device of lower resistance value. 

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||08:44
||So it allows current to pass through it.

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||08:48
||Hence it is connected in series.

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|| 08:52
||On the other hand voltmeter is a device with high resistance.

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||08:57
||If we connect it in series it will resist the flow of current in the circuit.

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|| 09:03
||That is why it is connected in parallel to allow the current to pass through it.

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|| 09:09
||Click on the '''Reset '''button.

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||09:12
||Change the value of '''Resistance''' to 250 ohms.

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|| 09:16
||Next click on '''Add resistor in series ''' to add 2 more resistances.

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||09:23
||Remember that we can only use three resistors in series.

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||09:28
||Click and move the cursor on the resistors in the circuit.

It shows 750 ohms. 

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||09:36
||This is the value of equivalent resistances in series.

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|| 09:41
||Now let us know how to calculate the series and parallel resistances.

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|| 09:47
||Next click on '''Add resistor in parallel ''' button.

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|| 09:52
||Note that a resistor of 250 ohms is added parallelly to the series resistances.

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|| 09:59
||Again click and move the cursor over the resistances.

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|| 10:04
||Here the value of equivalent resistance is 188 ohms.

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|| 10:10
||Let us see how the '''App '''has calculated the value of equivalent resistance. 

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|| 10:16
||The three resistance are in series combination, so we will add these resistances.

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||10:24
||This gives the value as 750 ohms.

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||10:28
||This 750 ohms resistance is connected in parallel with a 250 ohms resistance.

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||10:36
||To calculate parallel combination we use this formula.

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||10:41
||We will substitute the value of R1 as 750 ohms and R2 as 250 ohms. 

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||10:49
|| I have solved the equation and got the value as 187.5 ohms. 

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|| 10:56
||Note that the calculated value is comparable to the observed value.

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|| 11:02
||Let us solve a numerical based on series combination.

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|| 11:07
||Please pause the video and read the numerical.

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||11:11
||Now according to the numerical let us form a circuit on the interface.

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|| 11:17
||Click on the '''Reset''' button.

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||11:20
||Change the '''Voltage of the battery '''to 20 '''Volts''' and press '''Enter'''.

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|| 11:25
||Enter 110 ohms in '''Resistance''' text-box and press '''Enter'''.

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|| 11:32
||Click on '''Add resistor in series ''' button.

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||11:36
||Change the value of selected resistor to 50 ohms.

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|| 11:41
||Similarly add the third resistor and change the value to 180 ohms.

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|| 11:47
||As the resistors are connected in series we will add the resistances.

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||11:53
||So, the calculated value of resistance is 340 ohms.

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|| 11:59
||Next to calculate the current in the circuit we will use the ohm’s law.

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|| 12:05
||Rearrange the equation so as to calculate the value of current.

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|| 12:10
||Substitute the value of voltage and equivalent resistance.

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||12:15
||Click on the '''Amperage '''check-box to see the value of current.

Observe that the values are same.

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|| 12:24
||As an assignment solve this numerical.

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|| 12:29
||Let us summarize

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|| 12:31
||Using these '''Apps '''we have,
 
Verified Ohm’s Law.

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||12:36
|| Solved a numerical based on Ohm’s Law.

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||12:40
|| Drawn a graph to find the relation between voltage and current.

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||12:45
|| Solved a numerical based on series and parallel combination.

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||12:51
|| Calculated the value of current in the circuit.

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|| 12:55
||These Apps were created by Walter-Fendt and his team.

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||13:00
||The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.

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|| 12:08
||The'''Spoken Tutorial Project'''team, conducts workshops and gives certificates.

For more details, please write to us.

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|| 13:18
|| Please post your timed queries in this forum.

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|| 13:22
|| The Spoken Tutorial Project is funded by MHRD, Government of India.

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|| 13:28
||This is Himanshi Karwanje from IIT-Bombay. 

Thank you for joining.
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