Apps-On-Physics/C3/Ohm's-Law-and-its-Applications/English-timed
From Script | Spoken-Tutorial
| 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. |
