Tamil Nadu 12th Std Model Question Paper Physics

TAMIL NADU

od
M le
ap
P re
DOWNLOAD

No. of Printed Pages : 11
3267 (NS)
!3267NSPhysics! £vÄ Gs
Register Number

PART - III
C¯Ø¤¯À / PHYSICS

( uªÌ ©ØÖ® B[Q» ÁÈ / Tamil & English Version )

Põ» AÍÄ : 3.00 ©o ÷|µ® ] [ ö©õzu ©v¨ö£sPÒ : 70

Time Allowed : 3.00 Hours ] [Maximum Marks : 70

AÔÄøµPÒ : (1) AøÚzx ÂÚõUPЮ \›¯õP¨ £vÁõQ EÒÍuõ GߣuøÚa
\›£õºzxU öPõÒÍÄ®. Aa_¨£vÂÀ SøÓ°¸¨¤ß, AøÓU
PsPõo¨£õÍ›h® EhÚi¯õPz öu›ÂUPÄ®.
(2) }»® AÀ»x P¸¨¦ ø©°øÚ ©mk÷© GÊxÁuØS®
AiU÷PõikÁuØS® £¯ß£kzu ÷Ásk®. £h[PÒ ÁøµÁuØS
ö£ß]À £¯ß£kzuÄ®.

Instructions : (1) Check the question paper for fairness of printing. If there is any lack of
fairness, inform the Hall Supervisor immediately.

(2) Use Blue or Black ink to write and underline and pencil to draw diagrams.

£Sv & I / PART - I

SÔ¨¦ : (i) AøÚzx ÂÚõUPÐUS® Âøh¯ÎUPÄ®. 15x1=15
(ii) öPõkUP¨£mkÒÍ ©õØÖ ÂøhPÎÀ ªPÄ® Hئøh¯
Âøhø¯z ÷uº¢öukzxU SÔ±mkhß Âøh°øÚ²® ÷\ºzx
GÊuÄ®.
Note : (i) Answer all the questions.
(ii) Choose the most appropriate answer from the given four alternatives and
write the option code and the corresponding answer.

[ v¸¨¦P / Turn over

3267 (NS) 2

1. öÁÒøÍ {Ó JÎ-°øÚ EªÇ LED &°À £¯ß-£-kz-u¨-£-k® ö£õ-¸Ò :
(A) GaInN (B) SiC (C) AlGaP (D) GaAsP
Type of material which emits white light in LED :
(a) GaInN (b) SiC (c) AlGaP (d) GaAsP

2. öPõ-kU-P¨-£m-kÒÍ £hz-vÀ ¦ÒÎ ªß-Þm-h® +q BÚ-x ø©¯® O &À
EÒÍx. ©Ø-öÓõ¸ ¦ÒÎ (−Q) ªß-Þm-hzøu ¦ÒÎ A&¼-¸¢x ¦ÒÎ B&US
öPõsk Áµ ö\´-¯¨-£-k® ÷Áø»-°ß AÍÄ :

qQ  a 
(A) 4π a2  
2 (B) _È
0

−q Q 1  qQ 1 
(C)  4π 2
2a (D)  2
2a
 0 a   4 π0 a 
In the given diagram a point charge +q is placed at the origin O. Work done in taking
another point charge −Q from point A to point B is :

qQ  a 
(a) 2  (b) Zero
4 π0 a  2 

−q Q 1  qQ 1 
(c)  2
2a (d)  2
2a
 4π0 a   4 π0 a 

3 3267 (NS)

3. J¸ Aø»-Ä-Ö® LC _Ø-ÔÀ ªß-÷uU-Q-°À EÒÍ ö£¸© ªß-Þm-h® Q BS®.
BØ-Ó-»õ-Ú-x ªß ©Ø-Ö® Põ¢-u¨-¦-»[-P-ÎÀ \©-©õP ÷\ªU-P¨-£-k® ÷£õx,
ªß-Þm-hz-vß ©v¨¦ :
Q Q Q
(A) Q (B) 2 (C) 3
(D) 2
In an oscillating LC circuit, the maximum charge on the capacitor is Q. The charge on
the capacitor when the energy is stored equally between the electric and magnetic field
is :
Q Q Q
(a) Q (b) (c) (d)
2 3 2

4. •ußø© SÁõs-h® Gs (n) BÚx Av-P-›z-uõÀ ÷£õº Aq ©õ-v-›-°À
G»Um-µõ-Ûß vø\-÷Á-P® :
(A) Av-P-›U-S®, ¤ß¦ SøÓ-²® (B) Av-P-›U-S®
(C) SøÓ-²® (D) ©õ-Óõ-©À C¸U-S®
In Bohr Atom Model when the principal quantum number (n) increases the velocity of
electron :
(a) increases and then decreases (b) increases
(c) decreases (d) remains constant

5. ¤ß-Á-¸® ªß-_ØÖ G¢u »õ-âU ÷Pm-iØ-Sa \©-©õ-Úx :

(A) NAND ÷Pm (B) OR ÷Pm
(C) NOT ÷Pm (D) Ex-OR ÷Pm
The given electrical network is equivalent to :

(a) NAND gate (b) OR gate
(c) NOT gate (d) Ex-OR gate

[ v¸¨¦P / Turn over

3267 (NS) 4

6. ªß-÷uUQ Jß-Ôß ªß-÷ÚØ-Ó® ö\´-¯¨-£mh ªß-÷Úõm-h® 0.2 A GÛÀ
Ch¨-ö£-¯ºa] ªß-÷Úõm-h® :
(A) _È (B) 0.2 A (C) 0.4 A (D) 0.1 A
Charging current for a capacitor is 0.2 A, find the displacement current.

(a) zero (b) 0.2 A (c) 0.4 A (d) 0.1 A

7. 30 MHz •uÀ 400 GHz Áøµ-°-»õÚ Avº-öÁs ö|kU-P® £¯ß-£-k-Áx :

(A) ö\¯Ø-øPU-÷PõÒ uP-ÁÀ-öuõ-hº-¦
(B) uøµ Aø»¨ £µ-ÁÀ
(C) öÁÎ Aø»¨ £µ-ÁÀ
(D) Áõß Aø»¨ £µ-ÁÀ
The frequency range of 30 MHz to 400 GHz is used for :

(a) Satellite communication

(b) Ground wave propagation

(c) Space wave propagation

(d) Sky wave propagation

8. JÎ- ª ß öÁÎ- ÷ ¯ØÖ BØ- Ó À 1.235 eV öPõsh J¸ JÎ EnºÄ ªUP
E÷»õ- P z- u m- i ß «x 500 nm Aø»- } Í® öPõsh JÎ- £- k - Q - Ó x GÛÀ,
Eª- Ç ¨- £ - k ® JÎ G»Um- µ õß- P - Î ß C¯UP BØ- Ó À ( h=6.6×10 −34 Js
GÚU öPõÒP).
(A) 1.16 eV (B) 0.58 eV (C) 2.48 eV (D) 1.24 eV
A light of wavelength 500 nm is incident on a sensitive plate of photoelectric work
function 1.235 eV. The kinetic energy of the photo electrons emitted is :

(Take h=6.6×10−34 Js)

(a) 1.16 eV (b) 0.58 eV (c) 2.48 eV (d) 1.24 eV

5 3267 (NS)

9. J¸ ªß-÷uU-QUS AÎU-P¨-£-k® ªß-Ú-Êzu ÷ÁÖ-£õk V &¼-¸¢-x 2 V BP
Av- P - › U- P ¨- £ - k - Q - Ó x GÛÀ, ¤ß- Á - ¸ - Á - Ú - Á Ø- Ö Ò \›- ¯ õÚ •i-  - ø Úz
÷uº¢-öu-kU-P :
(A) Q ©ØÖ® C Cµs-k÷© ©õ-Óõ-©-¼-¸U-S®
(B) Q ©õ-Óõ-©-¼-¸U-S®, C C¸ ©h[-Põ-S®
(C) Q C¸ ©h[-Põ-S®, C C¸ ©h[-Põ-S®
(D) C ©õ-Óõ-©-¼-¸U-S®, Q C¸ ©h[-Põ-S®
If voltage applied on a capacitor is increased from V to 2 V, choose the correct conclusion.
(a) Both Q and C remain the same
(b) Q remains the same, C is doubled
(c) Q is doubled, C is doubled
(d) C remains the same, Q is doubled

10. ªß- ÷ Úõm- h ® £õ- ² ® }sh ÷|µõÚ Phz- v - ° - Ú õÀ R öuõ- ø »-  À EÒÍ
H÷u-Ý® J¸ ¦Ò-Î-°À HØ-£-k® Põ¢-u¨-¦-»® GÆ-ÁõÖ ©õ-Ö-£-k-Q-Óx ?
1 1
(A) R2 (B) R (C) (D) R
R2
Magnetic field at any point at a distance R due to a long straight conductor carrying
current varies as :

1 1
(a) R2 (b) R (c) (d)
R2 R

11. AqU-P¸ Qm-hz-umh ÷PõÍ Ái-Á® öPõs-hx GÛÀ {øÓ Gs A öPõs-h
AqU-P¸ Jß-Ôß £µ¨¦ BØ-ÓÀ GÆ-ÁõÖ ©õ-Ö-£-k® ?
(A) A5/3 (B) A2/3 (C) A4/3 (D) A1/3
The nucleus is approximately spherical in shape. Then the surface area of nucleus
having mass number A varies as :
(a) A5/3 (b) A2/3 (c) A4/3 (d) A1/3

12. um-øhU SÂ-ö»ß_ Jß-Ôß ÁøÍ-Ĩ-£-µ¨-¤ß ÁøÍÄ Bµ® 10 ö\.«. ÷©¾®
Auß JΠ»-PÀ Gs 1.5. SÂ-ö»ß-]ß um-øh¨-£-µ¨-¤ß «-x öÁÒÎ
§\¨-£m-hõÀ Auß SÂ-¯z-y-µ® :
(A) 20 ö\.«. (B) 5 ö\.«. (C) 10 ö\.«. (D) 15 ö\.«.
The radius of curvature of curved surface at a thin planoconvex lens is 10 cm and the
refractive index is 1.5. If the plane surface is silvered then the focal length will be :
(a) 20 cm (b) 5 cm (c) 10 cm (d) 15 cm

[ v¸¨¦P / Turn over

3267 (NS) 6

13. ªß _Ø-ÔÀ EÒÍ ªß-÷Úõm-hz-vß ©v¨¦ :

(A) 4 A (B) 1 A (C) 2 A (D) 3 A
The current in the circuit is :

(a) 4A (b) 1A (c) 2A (d) 3A

14. ¯[ Cµmøh ¤ÍÄ ÷\õ- u - ø Ú- ° À S 1 ©Ø- Ö ® S 2 GßÓ ¤Í- Ä - P - Î - ¼ - ¸ ¢x
öÁÎ- Á - ¸ ® JÎ Aø»- P Ò vøµ- ° À P ©Ø- Ö ® Q &I Aøh- ² ® ÷£õx
AÁØ-Ôß £õøu ÷ÁÖ-£õk •øÓ-÷¯ 0 ©Ø-Ö® λ 4 GÚ EÒÍ ÷£õx P ©Ø-Ö®
Q &ÂÀ JÎ-°ß ö\Ô-Ä-P-Îß ÂQ-u® :

(A) 4 : 1 (B) 3 : 2 (C) 2 :1 (D) 2 : 1

Two light waves from slit S1 and S2 on reaching points P and Q on a screen in Young’s
double slit experiment have a path difference zero and λ 4 respectively. The ratio of
light intensities at P and Q will be :

(a) 4:1 (b) 3:2 (c) 2 :1 (d) 2:1

7 3267 (NS)

15. m {øÓ- ² ® q ªß- ÷ Úõm- h - • ® öPõsh xP- ö ÍõßÖ V ªß- Ú - Ê z- u
÷ÁÖ-£õm-hõÀ •kU-Q-ÂU-P¨-£-k-Q-Ó-x. C¢u •kU-Q-ÂU-P¨-£mh xPÍõ-Úx
ö\[-Sz-uõP ö\¯À-£-k® Põ¢-u-¦-»z-v-ÝÒ Á¸® ÷£õx Auß «x ö\¯À-£-k®
Âø\ :

2q 3 BV 2q 3BV q 3B 2 V 2q 3B 2 V
(A) (B) (C) (D)
m3 m 2m m
A particle of mass m, carrying charge q is accelerated through a potential of V(Volt).
When this accelerated charge comes under the influence of perpendicular magnetic
field, the force acting on it is :

2q 3 BV 2q 3BV q 3B 2 V 2q 3B 2 V
(a) (b) (c) (d)
m3 m 2m m

£Sv & II / PART - II
SÔ¨¦ : GøÁ÷¯Ý® BÖ ÂÚõUPÐUS Âøh¯ÎUPÄ®. ÂÚõ Gs 24 &US
Pmhõ¯©õP Âøh¯ÎUPÄ®. 6x2=12
Note : Answer any six questions. Question number 24 is compulsory.
16. ©õ-`m-hÀ Gß-£-uß ö£õ-¸Ò GßÚ ?
What do you mean by doping ?

17. X & Pv-›ß £¯ß-PÒ ¯õøÁ ?
What are the uses of X-rays ?

18. J¸ C»m-]¯ ªß-©õØ-Ô-¯õ-Úx •uß-ø©a _¸Ò ©Ø-Ö® xøna _¸Ò-P-ÎÀ
•øÓ- ÷ ¯ 460 ©Ø- Ö ® 40,000 _Ø- Ö - P øÍU öPõs- k ÒÍx. ªß- © õØ- Ô - ¯ õ- Ú x
230 V AC ‰»z-x-hß CønU-P¨-£m-hõÀ, xøna-_-¸-Îß J¸ _Ø-ÔÀ E¸-ÁõÚ
ªß-Ú-Êz-u® Põs-P.
An ideal transformer has 460 and 40,000 turns in the primary and secondary coils
respectively. Find the voltage developed per turn of the secondary coil if the transformer
is connected to a 230 V AC main.

19. ¨µöÚÀ ©Ø- Ö ® ¨µõ÷ÚõL£º Âή¦ ÂøÍÄ- P - Ð US Cøh- ÷ ¯ EÒÍ
÷ÁÖ-£õ-k-PÒ ¯õøÁ ?
Distinguish between Fresnel and Fraunhofer types of diffraction.

[ v¸¨¦P / Turn over

3267 (NS) 8

20. JÎ-Ámh ªß-Û-ÓU-P® Gß-ÓõÀ GßÚ ?
What is corona discharge ?

21. uõ-Ĩ-£-µ¨¦ Gß-ÓõÀ GßÚ ?
What is skip area ?

22. {³m-›-÷Úõ-Âß £s-¦-PøÍ GÊ-x-P.
What are the properties of neutrino ?

23. X ©Ø-Ö® Y Gß-Ó Cµsk ö£õ-¸m-P-Îß Põ¢-u-©õU-S® ö\Ô-Ä-PÒ •øÓ-÷¯
500 Am−1 ©Ø-Ö® 2000 Am−1 Gß-P. AÁØ-Ôß Põ¢-u-©õU-S® ¦»z-vß ©v¨¦
1000 Am−1 GÛÀ C¸ ö£õ-¸m-P-Îß Põ¢u Hئ vÓß-P-Îß ÂQ-u® GßÚ ?
Two materials X and Y are magnetised whose intensity of magnetisation are 500 Am−1
and 2000 Am−1 respectively. The magnetising field is 1000 Am−1. What is the ratio
between the susceptibilities of the two material ?

24. ~s-÷nõU-QP
- Î
- À X &P-vº-PÐ
- US £v-»õP Hß G»Um-µõß £¯ß-£k
- z-u¨-£k
- Q
- Óx ?
Why electron is preferred over X-ray in microscope ?

£Sv & III / PART - III
SÔ¨¦ : GøÁ÷¯Ý® BÖ ÂÚõUPÐUS Âøh¯ÎUPÄ®. ÂÚõ Gs 33 &US
Pmhõ¯©õP Âøh¯ÎUPÄ®. 6x3=18
Note : Answer any six questions. Question number 33 is compulsory.
25. PõÀ-Á-÷Úõ «m-hº JßøÓ ÷ÁõÀm «m-h-µõP GÆ-ÁõÖ ©õØ-Ö-Áõ´ Gß-£øu
ÂÁ-›U-P-Ä®.
Explain the conversion of galvanometer into voltmeter.

26. 08C, &À J¸ {U-÷µõ® P®-¤-°ß ªß-uøh 10 Ω. Auß öÁ¨-£-{ø» ªß-uøh
Gs 0.004/8C GÛÀ, }›ß öPõv {ø»-°À Auß ªß-u-øh-ø¯U PnU-Q-kP.
Eß •iøÁ ÂÁõ-vUP-Ä®.
The resistance of a nichrome wire at 08C is 10 Ω. If its temperature coefficient of resistance
is 0.004/8C, find its resistance at boiling point of water. Comment on the result.

9 3267 (NS)

27. \µõ- \ › ¤øn¨¦ BØ- Ó À ÁøÍ- ÷ Põk öuõ- h º- £ õÚ •U- Q ¯ SÔ¨- ¦ - P Ò
¯õøÁ ?
What are the important inferences from the average binding energy curve ?

28. £hz- v À Põm- h ¨- £ m- k ÒÍ ªß _Ø- Ô À EÒ- Ï k ªß- Ú - Ê z- u ® V i =20 V,
VBE=0 V ©Ø-Ö® VCE=0 V GÛÀ IB, IC ©Ø-Ö® β&Âß ©v¨-¦-PÒ ¯õøÁ ?

In the circuit shown in the figure, the input voltage V i is 20 V, V BE =0 V and
VCE=0 V, what are the values of IB, IC and β ?

29. £UP Cøn¨-¤À ªß-÷uU-Q-PÒ CønU-P¨-£-k® ÷£õx ÂøÍ-²® öuõ-S-£-¯ß
ªß-÷uU-Sz vÓ-ÝU-PõÚ \©ß-£õm-iøÚ ö£Ö-P.
Derive the expression for equivalent capacitance, when capacitors are connected in
parallel.

30. ÷|ºz- v ø\ ªß- ÷ Úõm- h zøu Âh ©õ- Ö - v ø\ ªß- ÷ Úõm- h ® ]Ó¢- u x
Gß-£-uØ-PõÚ |ß-ø©-PÒ ©Ø-Ö® SøÓ-£õ-k-PÒ ¯õøÁ ?
What are the advantages and disadvantages of AC over DC ?

[ v¸¨¦P / Turn over

3267 (NS) 10

31. \©- à a_ öPõsh Cµsk JÎ ‰»[- P Ò SÖU- R mk ÂøÍ- ø Á
HØ-£-kz-x-Qß-ÓÚ. ö£¸© ©Ø-Ö® ]Ö-© JÎa-ö\-Ô-Ä-P-ÐUS Cøh-÷¯-²ÒÍ
ÂQ-uzøu Põs-P.
Two light sources of equal amplitudes interfere with each other. Calculate the ratio of
maximum and minimum intensities.

32. G»Um-µõ-Ûß i-¨-µõ´ Aø» }Íz-vØ-PõÚ \©ß-£õm-i-øÚ¨ ö£Ö-P.
Derive an expression for de-Broglie wavelength of electrons.

33. P®- ¤ - ° À- » õ uP- Á À- ö uõ- h º- ¤ À £s- ÷ £Ø- Ó - © õ- Ú x Âs- n - ø »U P®- ¤ - ° ß
AÍ-øÁU SøÓUP Eu-Ä-Q-Óx & ÂÍU-S-P.
Modulation helps to reduce the antenna size in wireless communication - Explain.

£Sv & IV / PART - IV
SÔ¨¦ : AøÚzx ÷PÒÂPÐUS® Âøh¯ÎUPÄ®. 5x5=25
Note : Answer all the questions.
34. (A) Põ¢- u ¨- ¦ - » z- ø ua \õº¢x P®- ¤ a- _ - ¸ - Î ß \õº- ¦ z vø\- ¯ - ø ©¨ø£
©õØ-Ö-Á-uß ‰»® ys-h¨-£-k® ªß-Û-¯US Âø\-UPõÚ ÷Põ-øÁø¯
u¸Â (Á-øµ-£-h® ÷uøÁ-°À-ø»).
AÀ»x
(B) Bia \©ß- £ õm- i øÚ Á¸-  zx, £U- P - Á õmk E¸¨- ö £- ¸ U- P z- v Ø- P õÚ
÷Põ-øÁ-ø¯¨ ö£Ö-P.
(a) Obtain the expression for the induced emf by changing relative orientation of the
coil with the magnetic field (Graph not necessary).
OR
(b) Derive the mirror equation and the equation for lateral magnification.

35. (A) }sh Cøn- ¯ õÚ ªß- ÷ Úõm- h ® £õ- ² ® C¸ Phz- v - P - Ð U- Q - ø h÷¯
HØ-£-k® Âø\-ø¯ ö£Ö-P.
AÀ»x
(B) ÷©Uì-öÁÀ \©ß-£õ-k-PøÍ öuõøP ~s-P-ou Ái-ÂÀ GÊ-x-P.
(a) Deduce the expression for the force between two long parallel current carrying
conductors.
OR
(b) Write down Maxwell equations in integral form.

11 3267 (NS)

36. (A) G»Um- µ õ- Û ß Aø» C¯À- ¤ øÚ ÂÁ- › U- S ® ÷hÂ- \ ß & öáº- © º
÷\õ-u-øÚø¯ ÂÁ-›U-P-Ä®.
AÀ»x
(B) (i) ÷£õº öPõÒ-øPø¯ £-¯ß-£-kzv øím-µ-áß Aq-Âß BØ-Ó-¾U-PõÚ
÷Põ-øÁ-ø¯z u¸-ÂU-P-Ä®.
(ii) ÷£õº Aq ©õ-v-›-°ß øím-µ-áß AqÂÀ EÒÍ G»Um-µõ-Ûß
BØÓÀ −3.4 eV GÛÀ, Auß ÷Põn E¢-uz-øuU Põs-P.
(a) Describe Davisson - Germer experiment which demonstrated the wave nature of
electrons.
OR
(b) (i) Derive an expression for the orbital energy of an electron in hydrogen atom
using Bohr theory.
(ii) An electron in Bohr’s hydrogen atom has an energy of −3.4 eV. What is
the angular momentum of the electron ?

37. (A) iµõß-]ì-hº, Aø» C¯Ø-Ô-¯õP ö\¯À-£-k® Âuz-øu- Â-Á-›U-P-Ä®.
AÀ»x
(B) ªß- y s- i a_Ø- Ô À ªß- Ú - Ê zu ÷ÁÖ- £ õk ©Ø- Ö ® ªß- ÷ Úõm- h ®
Cøh-÷¯ EÒÍ Pm-hz öuõ-hºø£ Põs-P.
(a) Explain the working of the transistor as an oscillator.
OR
(b) Find out the phase relationship between voltage and current in a pure inductive
circuit.

38. (A) {ø»-ªß-Û-¯-¼ß Põì Âv-ø¯ TÖP. ªß-Þm-h® ö£ØÓ •i-Â-»õ
}Í-•ÒÍ P®-¤-°-ÚõÀ HØ-£-k® ªß-¦-»z-vØ-PõÚ \©ß-£õmøh ö£Ö-P.
AÀ»x
(B) ªß- Ú - Ê z- u - © õ- Û ø¯ £¯ß- £ - k zv C¸ ªß- P - » [- P - Î ß ªß- Û - ¯ US
Âø\-PÒ GÆ-ÁõÖ J¨-¤-h¨-£-k-Qß-ÓÚ ?
(a) State Gauss Law in electrostatics. Obtain an expression for Electric field due to an
infinitely long charged wire.
OR
(b) How the emf of two cells are compared using potentiometer ?

-oOo-

[ v¸¨¦P / Turn over

.