phy_notes\alevel_6tas\hkal physics tas lab menu 12-2

8/10/2019 Phy_notes\Alevel_6tas\HKAL Physics TAS Lab Menu 12-2

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Carmel Holy Word Secondary School Advanced physics TAS laboratory menu.

Experiment 12 : Estimation o the !avelen"th o li"ht usin" plane diraction "ratin".

#ame : Class : $ % &roup :

$'ull (eport%

)reliminary *uestions

1. The li"ht emitted by a ilament lamp has many properties. )lease state t!o o them.

2. 'or a diraction "ratin" o +,, lines per mm- ind its slit separation.

+. What is the evidence that li"ht is one ind o !aves/

0. Write do!n the conditions or rays o li"ht rom t!o sources to orm an intererence pattern.

HA )hysics TAS lab menu 12 130


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#ame : Class : $ % &roup :

Experiment 12 : Estimation o the !avelen"th o li"ht usin" plane diraction "ratin".

4b5ective

6sin" plane diraction "ratin" to estimate the !avelen"th o li"ht and learn the techni*ues in

usin" a spectrometer.

Apparatus

1. 1 diraction "ratin" !ith +,, lines per mm

2. 1 ray box

+. 1 12 7 po!er supply

0. 1 clip

8. 2 metre rules

9. 2 lon" pins. + color ilters $red- "reen- blue%

;. 1 spectrometer


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the middle o the red band o the irst order spectrum. ?ou may place a red ilter in ront

o the ray box or locatin". (epeat this step or the ri"ht hand side !ith another pin.

=easure and record the separation o the t!o pins- 2x.

0. (epeat step + or "reen and then blue li"ht.

8. Calculate the an"les o diraction or red- "reen and blue li"ht. Hence- ind the

correspondin" !avelen"ths or these three li"hts. 'ind their percent errors by comparin"

!ith the standard values. (ecords all the results in Table 1.

)recautions

1. The to! positions should be symmetrical about the ray box.

@ata

(ed &reen lue

Separation bet!een pins

2 x$ %

An"le o diraction

$ %

=easured !avelen"th

$ %

Standard !avelen"th

$ %

)ercent error o!avelen"th

Table 1 TeacherBs si"nature :

Experiment 2 : =easurin" the an"le o diraction by spectrometer

Setup

t e l e s c o p e

o c u s s i n "

s c r e ! v e r n i e r s c a l e

d i r a c t i o n" r a t i n "

c o l l i m a t o r

c o l l i m a t o r s c r e !

)rocedures

1. Ad5ustment o the spectrometer.

HA )hysics TAS lab menu 12 +30


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1.1 'ocus the telescope to a distant ob5ect by ad5ustin" the ocusin" scre!. Turn the

telescope into line !ith the collimator.

1.2 )lace the ray box on a laboratory 5ac and illuminate the slit o the collimator. Ad5ust

the collimator until ilament o the lamp is clearly seen throu"h the telescope.

2. =easurement o the an"le o diraction

2.1 7ertically mount the diraction "ratin" on the platorm at ri"ht an"le to the optical

axis o the telescope.

2.2 Turn the telescope to your let hand side until the red color o the irst order

spectrum coincides !ith the cross!ires. Dnsert the appropriate ilter may help

locatin" this position. (epeat this step or the position on your ri"ht hand side.

(ecord the t!o vernier readin".

2.+ (epeat step 2.2 or "reen and then blue li"ht.

2.0 Calculate the an"les o diraction or red- "reen and blue li"ht. Hence- ind the

correspondin" !avelen"ths or these three li"hts. 'ind their percent errors bycomparin" !ith the standard values. (ecords all the results in Table 2.

)recautions

1. The slit o the collimator should be as narro! as possible or the accuracy o the measured

an"le o the diraction.

@ata

(ed &reen lue7ernier readin" 1

7ernier readin" 2

An"le o diraction

$ %

=easured !avelen"th

$ %

Standard !avelen"th

$ %

)ercent error o

!avelen"th

Table 2 TeacherBs si"nature :

@iscussion

1. The t!o experiments are most suitable to measure !hich li"ht $red- "reen or blue%/ )lease

explain it.

2. What are the sources o error o the t!o experiments/ Ho! can you improve the accuracy

o the experiments/



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Conclusion

1. State the ma5or results o these t!o experiment.


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