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

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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.

Contributors and Content Editors

PoojaMoolya