Apps-On-Physics/C3/Convex-Lenses/English - Revision history

Madhurig at 11:07, 13 May 2020

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Madhurig at 11:06, 13 May 2020

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Madhurig at 10:28, 13 May 2020

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Karwanjehimanshi95 at 12:12, 6 May 2020

2020-05-06T12:12:29Z

Nancyvarkey at 06:44, 6 May 2020

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Karwanjehimanshi95 at 06:01, 28 April 2020

2020-04-28T06:01:16Z

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Karwanjehimanshi95: Created page with " {|border=1 |- || '''Visual Cue ''' || '''Narration''' |- || '''Slide Number 1 ''' '''Title Slide''' || Welcome to the spoken tutorial on '''Convex Lenses.''' |- || '''Slid..."

2020-04-27T12:18:01Z

Created page with " {|border=1 |- || '''Visual Cue ''' || '''Narration''' |- || '''Slide Number 1 ''' '''Title Slide''' || Welcome to the spoken tutorial on '''Convex Lenses.''' |- || '''Slid..."

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{|border=1
|-
|| '''Visual Cue '''
|| '''Narration'''

|-
|| '''Slide Number 1 '''

'''Title Slide'''
|| Welcome to the spoken tutorial on '''Convex Lenses.'''

|-
|| '''Slide Number 2 '''

'''Learning objective '''
|| At the end of this tutorial you will be able to,

Change the focal length and see the kind of image formed.

Change the object distance and object height and see the kind of image formed.

Calculate the magnification and length of the telescope tube.

|-
|| '''Slide Number 3'''

'''System Requirements'''
|| Here I am using,

Ubuntu Linux OS version 16.04

Firefox Web Browser version 62.0.3

|-
|| '''Slide Number 4'''

'''Pre-requisites'''

[https://spoken-tutorial.org/ https://spoken-tutorial.org/] '''
|| To follow this tutorial, learner should be familiar with topics in '''Apps on Physics'''.

For the Pre-requisites tutorials please visit this site.

|-
|| Point to the file in the downloads folder
|| I have already downloaded '''Apps on Physics '''to my '''Downloads''' folder.

|-
|| '''Slide Number 5'''

'''Apps on Physics'''
|| In this tutorial we will use,

'''Image Formation by Converging Lenses '''and

'''Refracting Astronomical Telescope Apps'''.

|-
|| Right click on '''imageconverginglens_en.htm''' file.

Select the '''Open With Firefox web Browser''' option.

Cursor on the '''App'''.
|| Right click on '''imageconverginglens_en.htm '''file.

Select the '''Open With Firefox web Browser '''option'''.'''

'''Image Formation by Converging Lenses App''' opens in the browser.

|-
|| Point to the convex lens in the App.
|| The '''App''' shows a ray diagram of the convex lens.

|-
|| '''Slide Number 6'''

'''Converging Lense'''

Show the ray diagram with all the positions.

'''The image is given at the end of this script.'''
|| Before moving to the App let us first be familiar with ray diagrams.

Let us define principal axis.

It is an imaginary line passing through the optical center.

A vertical axis divides the lens into two equal halves.

There are four positions on the principal axis, these positions are 2F , F , F’ and 2F’.

F is the focal length and 2Fis the twice the distance of focal length.

F’ and 2F’ is on the opposite side of the lense with the same distance as F and 2F’.

|-
|| Open App.
|| Let us open the App.

|-
|| Point to the scale at the bottom of the yellow panel.
|| Let us use the scale to spot the positions of focal length F and 2F.

|-
|| Point to show the Zero on the scale.

Point to '''Object distance'''.

Move the screen using the pressed mouse.
|| Initially the object is placed at the zero position of the scale.

The distance of the object from the lens is 50 cm.

The vertical black line beyond the lens is a screen.

This screen can be moved back and forth.

|-
|| Point to the blue arrow.
|| Blue arrow indicates the height of the object.

It is placed beyond 2F.

|-
||
|| 2F is twice the distance of the focal length F.

|-
|| Show it on the scale.
|| From the App, the focal length is 10 cm, so position of 2F has to be at 20 cm.

|-
|| Point to the green arrow.
|| Green arrow indicates the image formed by the convex lens.

|-
|| In the green control panel point to '''Focal length''',

'''Object distance''', and '''Object height'''.
|| In the green control panel we can edit the values of the following parameters.

|-
|| Edit the '''Focal length''' to 20 '''cm''' and press '''Enter'''.
|| Change the '''Focal length''' value of the '''lens''' to 20 '''cm '''and press''' Enter'''.

|-
|| Point to the radio buttons Principle light rays and Bundle of light rays.
|| At the bottom of the green panel there are two radio buttons.

'''Principal light rays''' and '''Bundle of light rays'''.

|-
|| Point to Principal light rays.
|| By default '''Principal light rays '''option is selected.

|-
|| Click on the drop down list.
|| A drop down is provided to '''Emphasize''' different paramet ers.

|-
|| Click on the drop down and Select''' Object distance.'''
|| From the drop down list, select '''Object distance.'''

|-
|| Point to the object distance.
Point to blinking line.
|| Observe that the '''App '''emphasizes the object distance using a blinking line.

The blinking line disappears after sometime.

|-
|| Drag the object(blue arrow) to show the changes in object distance and height.
|| We can also change the object distance and object height by dragging the object.

As we drag the value in the text-box changes accordingly.

|-
|| Press the '''F5 '''key on the keyboard
|| Press the '''F5 '''key on the keyboard to refresh the''' App'''.

|-
|| Edit the '''Object height''' to 15 '''cm''' and press '''Enter'''.
|| Now change the value of '''Object height''' to 15 cm.

|-
|| Cursor on the ray diagram.
|| Let us learn about the ray diagram.

|-
|| Point to the ray which is parallel to the optical axis.

Point to the ray.
|| The ray emerging from the '''object''' is parallel to the principal axis of the lens.

This ray after refraction passes through the second principal focus F’.

|-
|| Point to the second ray of light which passes without any deviation.
|| A second ray of light passes through the optical center of the lens.

This ray after refraction emerges without any deviation.

|-
|| Point to the last ray which parallel to the optical axis after refraction.
|| A third ray passes through the first principal focus F.

This ray, after refraction is parallel to the principal axis.

|-
|| Point to show the meeting point of the rays.
|| The image is formed, at point of intersection of the three rays.

|-
||
|| Let us change the position of the object and see where the image appears.

|-
|| Edit the value of focal length to 20 cm.
|| Change the focal length to 20 cm.

|-
|| Edit the value of '''Object distance '''to 35 cm and '''Object height''' to 10 cm.
|| Change the '''Object distance '''to 40 cm and '''Object height''' to 10 cm.

|-
|| In the control panel point to the '''Kind of image''' formed.

'''real, inverted''' and '''equal dimension'''.
|| The '''Kind of image '''formed is '''real, inverted '''and '''equal dimension'''.

|-
|| Point to show the values of following.

'''Object distance'''

'''Object height'''

'''Image distance '''

'''Image height.'''
|| This is the condition for''' 2F''', when object is at''' 2F''' the image will appear at '''2F'''’.

Here the object distance and height will be equal to image distance and height.

|-
|| Drag the object between '''2F''' and '''F'''.

Drag the object to 10 cm.
|| Drag the object between the '''2F''' and '''F.'''

Drag the object to''' 10 cm.'''

Here we can use the scale to take the measurement.

|-
|| Point to the image formed.
|| Observe that image is formed beyond '''2F’''' and the image is '''real''',''' inverted''' and '''magnified'''.

|-
|| Drag the object between''' F '''and optic center.

Drag it to 30 cm.
|| Drag the object between '''F''' and optic center.

Drag the object to 30 cm.

|-
|| Point to the image (green arrow).
|| Observe that image is formed at the first principal focus behind the object.

|-
|| '''Slide Number 7'''

'''Assignment'''
|| As an assignment

Change the focal length of a convex lens to 10 cm and its object distance to 15 cm.

What characteristics of the image do you observe?

|-
||
|| Let us move on to next '''App'''.

|-
|| To open the '''App''' right click on '''refractor_en.htm.

Select option '''Open with Firefox Web Browser.'''
|| To open the''' App''' right click on '''refractor_en.htm''' file.

Select the option '''Open with Firefox Web Browser'''.

|-
|| Point to the''' App.'''
|| The '''App '''opens with a '''Refracting Astronomical Telescope.'''

|-
|| Point to the bigger lens.
|| In the yellow panel the bigger lens is the objective.

The objective has a large focal length.

|-
|| Point to the smaller lens.
|| Here the smaller lens is an Eyepiece.

|-
|| Point to the red coloured rays.
|| The red coloured rays indicate the light from a distant object.

|-
|| Move the cursor to show the path of the rays.
|| Light rays from a distant object enter the objective lens.

After refraction a real image is formed at the second focal point.

|-
|| Point to the eyepiece.
|| Then the eyepiece magnifies the image.

The image formed is enlarged and inverted.

|-
|| Point to the black circle which is at the bottom right corner.
|| The magnified image of six brightest star of the pleiades is seen in the black circle.

|-
|| In the green control panel point to '''Focal length''' of '''Objective '''and '''Eyepiece'''.
|| In the green panel, Focal lengths of objective and Eyepiece can be edited.

|-
|| Highlight this sentence from the '''App'''(2nd para 1st line).
|| Here we can vary the '''Focal lengths '''of '''Objective''' and '''Eyepiece''' from 0.05 '''m '''to 0.5 '''m'''.

|-
|| Point to the '''Angles'''

'''Objective '''and '''Eyepiece'''.

Point to '''Magnification'''.
|| As per the changes in the focal lengths,

'''App '''calculates '''Angles''' and '''Magnification'''.

|-
|| Scroll down to see the formula for magnification.
|| At the bottom of the screen '''App''' has given the formula for magnification.

|-
|| Point to the formula.
|| '''v'''<nowiki>= - f</nowiki>1/ f2 

Here v is the magnification

f1 is the focal length of Objective and

f2 is the focal length of Eyepiece.

|-
||
|| Let us calculate the magnification using the data from the '''App'''.

|-
|| Edit the value of '''Focal length''' of the '''Objective''' to 0.45 m

and '''Eyepiece''' to 0.1''' m.'''
|| Change the '''Focal length''' of the '''Objective''' to 0.45 '''m '''and '''Eyepiece''' to 0.1''' m.'''

|-
|| Point to the observed value.
|| Observe that '''App '''has calculated the value for magnification.

|-
|| Point to the black circle.
|| Notice the changes in the black circle.

If we increase the focal length of the Objective image will be more magnified.

|-
||
|| Let us now calculate the length of the telescope tube.

|-
|| Press '''F5''' key on the keyboard.
|| Change the '''Focal lengths '''of the '''Objective '''and '''Eyepiece''' to their default values.

Press F5 key on the keyboard to restart the '''App'''.or we can just refresh the page.

|-
|| '''Slide Number 9'''

'''Telescope Tube'''

'''Length of the tube is sum of the focal lengths'''

'''of objective and eyepiece'''.

'''L= f1 + f2'''

'''<nowiki>= 0.50 + 0.10</nowiki>'''

'''<nowiki>= 0.6 m</nowiki>'''
|| Formula to calculate length of the tube is,

L= f1 + f2.

Here f1 is focal length of Objective and f2 is focal length of Eyepiece.

Substitute the focal lengths and calculate the length of the telescope tube.

Observe that the length of the telescope is 0.6 '''m'''.
|-
|| Drag the rays and point to the changes in the '''Angles''' and the '''Magnification.'''
|| Note that as we drag the rays, there will be changes in both '''Angles''' and '''Magnification'''.

|-
||
|| This happens because the focal lengths of both objective and eyepiece changes.

|-
|| Edit the values of '''Focal length''' of '''Objective '''to 0.1 '''m'''

and''' Eyepiece''' to 0.5''' m'''.
|| Now reverse the '''Focal lengths '''of the '''Objective''' and '''Eyepiece'''.

|-
|| Point to the single dot in the second black circle.
|| Observe that the six brightest stars of pleiades appear to be a single point.

|-
||
|| This is because the focal length of the '''Objective''' is smaller than that of the '''Eyepiece'''.

|-
|| '''Slide Number 10'''

'''Assignment'''

An astronomical telescope has an objective of focal length

0.45 m and an eyepiece of focal length 0.25 m.

Find the magnification produced by the telescope.

Verify the calculated value with the ones shown in the App.'''
|| As an assignment solve this numerical.

|-
||
|| Let us summarise

|-
|| '''Slide Number 11'''

'''Summary'''
|| Using these '''Apps''' we have,

Changed the focal length and saw the kind of image formed

Changed the object distance and object height and saw the kind of image formed

Calculated the magnification and length of the telescope tube.

|-
|| '''Slide Number 12'''

'''Acknowledgement'''

These Apps are created by Walter-fendt and his team.

|| These Apps are created by Walter-fendt and his team.

|-
|| '''Slide Number 13'''

'''About Spoken Tutorial project.'''

|| The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

|-
|| '''Slide Number 14'''

'''Spoken Tutorial workshops.'''

|| The '''Spoken Tutorial Project '''team,

conducts workshops and gives certificates.

For more details, please write to us.

|-
|| '''Slide Number 15'''

'''Forum for specific questions:'''

|| Please post your timed queries in this forum.

|-
|| '''Slide Number 16'''

'''Acknowledgement'''
||The Spoken Tutorial Project is funded by MHRD, Government of India.

|-
||
|| This is Himanshi Karwanje from IIT-Bombay.

Thank you for joining.
|-
|}

@@ Line 442: / Line 442: @@
 * Find the magnification produced by the telescope.
-* Verify the calculated value with the ones shown in the '''App.'''
+* Verify the calculated value with the one shown in the '''App.'''
 || As an assignment solve this numerical.

@@ Line 39: / Line 39: @@
 || To follow this tutorial, learner should be familiar with '''Apps on Physics'''.
-For the prerequisite tutorials please visit this site.
+For prerequisite tutorials please visit this site.
 |-
@@ Line 63: / Line 63: @@
 || Right-click on '''imageconverginglens_en.htm '''file.
-Select the '''Open With Firefox Web Browser '''option.
+Select '''Open With Firefox Web Browser '''option.
 '''Image Formation by Converging Lenses App''' opens in the '''browser'''.
@@ Line 176: / Line 176: @@
 |-
 || Press '''F5 '''key on the keyboard
-|| Press '''F5 '''key on the keyboard to refresh the''' App'''.
+|| Press '''F5 '''key on the keyboard to refresh the '''App'''.
-−
 |-
 || Edit the '''Object height''' to 15 '''cm''' and press '''Enter'''.
@@ Line 284: / Line 283: @@
 |-
 || Cursor on the interface.
-|| Let us move on to next '''App'''.
+|| Let us move to next '''App'''.
 |-
@@ Line 296: / Line 295: @@
 |-
 || Point to the''' App.'''
-|| The '''App '''opens with a '''Refracting Astronomical Telescope.'''
+|| The '''App '''opens with '''Refracting Astronomical Telescope.'''
 |-
@@ Line 369: / Line 368: @@
 |-
-||
+|| Cursor on the interface.
 || Let us calculate the magnification using the data from the '''App'''.
@@ Line 387: / Line 386: @@
 |-
-||
+||Cursor on the interface.
 || Let us now calculate the length of the telescope tube.
@@ Line 428: / Line 427: @@
 |-
 || Point to the single dot in the second black circle.
-|| Observe that the six brightest stars of pleiades appear to be a single point.
+|| Observe that the six brightest stars of pleiades appears to be a single point.
 |-
@@ Line 439: / Line 438: @@
 '''Assignment'''
-*An astronomical telescope has an objective of focal length 0.45 m and an eyepiece of focal length 0.25 m.
+* An astronomical telescope has an objective of focal length 0.45 m and an eyepiece of focal length 0.25 m.
-*Find the magnification produced by the telescope.
+* Find the magnification produced by the telescope.
-*Verify the calculated value with the ones shown in the '''App.'''
+* Verify the calculated value with the ones shown in the '''App.'''
 || As an assignment solve this numerical.

@@ Line 1: / Line 1: @@
 {|border=1
 |-
@@ Line 17: / Line 16: @@
 || At the end of this tutorial you will be able to,
-*Change the focal length and see the kind of image formed.
+* Change the focal length and see the kind of image formed.
-*Change the object distance and object height and see the kind of image formed.
+* Change the object distance and object height and see the kind of image formed.
-*Calculate the magnification and length of the telescope tube.
+* Calculate the magnification and length of the telescope tube.
 |-
@@ Line 29: / Line 28: @@
 || Here I am using,
-*Ubuntu Linux OS version 16.04
+* Ubuntu Linux OS version 16.04
-*Firefox Web Browser version 62.0.3
+* Firefox Web Browser version 62.0.3
 |-
@@ Line 52: / Line 51: @@
 || In this tutorial we will use,
-*'''Image Formation by Converging Lenses '''and
+* '''Image Formation by Converging Lenses '''and
-*'''Refracting Astronomical Telescope Apps'''.
+* '''Refracting Astronomical Telescope Apps'''.
 |-

@@ Line 90: / Line 90: @@
 These positions are 2F , F , F’ and 2F’.
-F is the focal length and 2F is the twice the distance of focal length.
+F is the focal length and 2F is twice the distance of focal length.
 F’ and 2F’ are on the opposite side of the lens with the same distance as F and 2F.
@@ Line 457: / Line 457: @@
 || Using these '''Apps''' we have,
-*Changed the focal length and saw the kind of image formed.
+*Changed the focal length and seen the kind of image formed.
-*Changed the object distance and object height and saw the kind of image formed.
+*Changed the object distance and object height and seen the kind of image formed.
 *Calculated the magnification and length of the telescope tube.