This is the edited version of the investigatory project on physics with different topic(To construct a switch using transistor and plot a graph bw input output voltage) originally created by rahul only intention to upload this project is to help other class 12 appearing students ................... so they do not have to kill there time in making these useless projects THANKS HOPE IT HELPED ................comment what you think...................................

1. `
2015-16
Himanshu
Soni
K V ORDNANCE
FACTORY KATNI
PHYSICS
INVESTIGATORY PROJECT

2. KENDRIYAVIDYALAYA NO.1
ORDNANCE FACTORYKATNI
DEPARTMENTOF PHYSiCS
CERTIFICATE
This is to certify that Himanshu Soni, a student of class XII-A has successfully completed the
research on the below mentioned project under the guidance of Mr. S.K Tiwari ( Subject
Teacher ) during the year 2015-16 in partial fulfillment of physics practical examination
conducted by AISSCE, New Delhi.
Signature of external examiner
Signature of physics teacher

3. ACKNOWLEDGEMENT
Intheaccomplishmentofthisprojectsuccessfully,many people
havebest owneduponmetheirblessings andtheheart pledged
support,thistimeIamutilizing tothankallthepeoplewho
havebeenconcernedwithproject.
Primarily Iwouldthankgodforbeingabletocompletethis
projectwithsuccess. ThenIwouldliketothankmyprincipal
Ms.ChandralekhaG.Rand ChemistryteacherMs.Seema
tamrakar,whosevaluableguidancehasbeentheonesthat
helpedmepatchthisprojectandmakeit fullproofsuccesshis
suggestionsand hisinstructionshasservedas themajor
contributortowardsthecompletionoftheproject.

4. ThenI wouldliketothankmyparentsand friendswhohave
helpedmewiththeirvaluablesuggestionsand guidancehas
beenhelpfulinvariousphasesofthecompletionoftheproject.
Lastbutnot theleast Iwouldliketothankmyclassmates who
havehelpedmealot.
INDEX
1. CERTIFICATE OF EXCELLENCE
2. ACKNOWLEDGEMENT
3. AIM OF PROJECT
4. INTRODUCTION
5. THEORY
6. APPARATUS REQUIRED
7. PROCEDURE FOLLOWED
8. OBSERVATION

5. 9. CONCLUSION
10. BIBLIOGRAPHY
AIM OF THE
EXPERIMENT

6. To construct a switch using a transistor and
to draw the graph between the input and
output voltage and mark the cut-off,
saturation and active region.
THEORY
In the common emitter circuit of a transistor, emitter base make
input section and is forward biased and emitter collector junction
make output section and is reverse biased .
Appling Kirchhoff’s law, for input circuit
VBB = IBRB + VBE
And for output circuit
VCE = VCC - ICRC
But VBB = Vi and VCC = Vo, Then
Vi = IBRB + VBE
Vo =VCC - ICRC
The variation in the output voltage with respect to the variation in
input voltage for a Si transistor are shown in figure.

7. CIRCUIT DIAGRAM

8. AIM :
To construct a switch using a transistor and to draw
the graph between the input and output voltage and
mark the cut-off, saturation and active region.
APPARATUS REQUIRED:
An npn transistor (BC 108 or 2Tx300),a 3 volt battery ,two high
resistance (100kohm,10kohm),a six volt battery, a bulb(6V,0.06A),0-3

9. volt meter, one0-6 volt voltmeter, two one way keys, connection
wires.
PROCEDURE:
 Make a circuit diagram
 Make all connections neat, clean and tight

10.  Note least count and zero error of voltmeters
 Make the voltmeters reading zero in Vi and Vo
 Increase the voltage from input battery Vbb from 0 to 0.6V
and read it in voltmeter Vi and record the reading in voltmeter
Vo.
 Further increase the input voltage (0.6<Vi <=1V) and record
the reading in both voltmeters. The reading in voltmeter Vo,
decreases continuously.
 With further increase in Vi (Vi>1V) and again record the
reading in both voltmeters. The reading in the output
voltmeter is found to decrease in further toward zero
through it may never be zero.
 Plot the reading of Vi and Vo by taking Vi on x-axis and Vo the
y-axis. The graph will be similar to figure as shown in figure.
OBSERVATIONS
1. Least count of voltmeter Vi =
2.Least count of voltmeter Vo =

11. 3.Zero error of voltmeter Vi =
4.Zero error of voltmeter Vo =
Inpur voltage
Vi (v)
Output voltage
Vo(V)
0
0.1
0.2
0.3
0.4
0.5
………..
1.3
1.4
1.5
CONCLUSION

12. 1. When the input voltage Vi (0 to 0.6) then transistor is in
cut off region . The transistor do not act.
2.When the input voltage Vi (0.6<Vi <=1.0) V then transistor
is in active region. The transistor act.
3.The transistor incut off region act as switch in off
positon and in saturation region. The transistor act.
4.The transistor in cut off region act as switch in off
position and in saturation region it actas switch in on
position .
PRECAUTIONS
1. All connection should be neat, clean and tight .
2.The input voltage should be increase gradually.
RESULT
The variation in the output voltage with respect to the variation in
input voltage for a Si transistor is observed.
Biblography

13. 1. Website
 www.wikipedia.org
 www.google.com
 www.yahoo.com
2. BOOKS:
 Comprehensive Practical Manual
 NCERT Class XII