Lecture notes on strength of materialsFull description
LAPORAN KOEF MUAI THERMALDeskripsi lengkap
questions from combustion in IC engine
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Chapter # 33
Thermal and Chemical Effects of Electric Current
[1]
Objective - I
1.
Which of the following plots may represent the thermal energy produced in a resistor in a given time as a function of the electric current ? fuEu esa ls dkSulk oØ fdlh fuf'pr le; esa fo|qr /kkjk ds Qyu ds :i esa fdlh izfrjks/k esa mRiUu Å"ek ÅtkZ O;Dr djrk gS -
Sol.
A
(A*) 1
(B) 2
(C) 3
(D) 4 u
UAB = OAB +
1 b 2 2 AB a
t UAB aAB t
1 b t2 2 AB
t
2.
A constant current i is passed through a resistor. Taking the temperature coefficient of resistance into account, indicate which of the plots shown in fig. best represents the rate of production of thermal energy in the resistor. fdlh izfrjks/k ls fu;r /kkjk i izokfgr gksrh gSA rki izfrjks/k xq.kkad dks izHkkoh ekurs gq, fuEu fp=k esa dkSulk oØ fdlh izfrjks/k esa m"ek ÅtkZ mRiUu gksus dh nj dks vf/kd lgh iznf'kZr djrk gS -
Sol.
A
(A) 1
(B) 2
(C) 3
dv dt
(D*) 4
d
t UAB aAB
1 b 2 2 AB
× t d × dt 3.
duAB aAB bAB t dt
Consider the following statements regarding a thermocouple. (a) The neutral temperature does not depend on the temperature of the cold junction. (b) The inversion temperature does not depend on the temperature of the cold junction. (A) Both a and b are correct. (B*) a is correct but b is worng (C) b is correct but a is wrong (D) Both a and b are wrong
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Chapter # 33
Sol.
4.
Sol. 5.
Ans.
6.
Sol.
7.
Sol.
Thermal and Chemical Effects of Electric Current
[2]
rki&oS|qr ;qXe ds fy;s fuEu dFkuksa ij fopkj dhft;s (a) mnklhu rki B.Mh laf/kds rki ij fuHkZj ugha djrk gSA (b) A lR; gS rFkk B vlR; gSA (A) a o b nksuksa lR; gSA (B*) a lR; gS rFkk b vlR; gSA (C) b lR; gS rFkk a vlR; gSA (D) a o b nksuksa vlR; gSA
B At cold function :Qn - QC = Qi - Qn where Qn neutral temperture Qi inversion temperature Qc thermo-couple temperature. The neutral temperature does not depend on the temperature of the cold function. The inversion temperature does depend on the temperature of the cold function. The heat developed in a system is propertional to the current through it. (A) It cannot be Thomson heat (B) It cannot be Peltier heat (C*) It cannot be Joule heat (D) It can be any of the three heats mentioned above fdlh fudk; esa mRiUu m"ek blls izokfgr /kkjk ds lekuqikrh gS (A) ;g FkkWelu m"ek ugha gks ldrh gSA (B) ;g isYVh;j m"ek ugha gks ldrh gSA (C*) ;g twy m"ek ugha gks ldrh gSA (D) ;g mDr rhuksa m"ekvksa esa ls dksbZ Hkh ugha gks ldrh gSA C Consider the following two statements (a) Free-electron density is different in different metals. (b) Free-electron density in a metal depends on temperature. Seebeck effect is caused (A*) due to both a and b (B) due to a but not due to b (C) due to b but not due to a (D) neither due to a nor due to b fuEufyf[kr nks dFkuksa ij fopkj dhft;s (a) fHkUu&fHkUu /kkrqvksa esa eqDr bysDVªkWu ?kuRo fHkUu&fHkUu gksrk gSA (b) /kkrq esa eqDr bysDVªkWu ?kuRo rki ij fuHkZj djrk gSA lhcsd izHkko mRiUu gksrk gS % (A*) a o b nksuksa ds dkj.k (B) a ds dkj.k] fdUrq b ds dkj.k ugha (C) b ds dkj.k] fdUrq a ds dkj.k ugha (D) u rks a ds dkj.k u gh b ds dkj.k A See back effect is caused due to free electron density is different in different metals or freeelectron density in a metal depends on temperature. Consider the statement a and b in the previous question. Peltier effect is caused (A) due to both a and b (B*) due to a but not due to b (C) due to b but not due to a (D) neither due to a nor due to b fiNys iz'u esa fn;s x;s dFkuksa A rFkk B ij fopkj dhft;sA isYVh;j izHkko mRiUu gksrk gS (A) a o b nksuksa ds dkj.k (B*) a ds dkj.k] fdUrq B ds dkj.k ugha (C) b ds dkj.k] fdUrq a ds dkj.k ugha (D) u rks a ds dkj.k u gh b ds dkj.k B Pelties effect is caused due to free electron density is different in different metals. Consider the statements a and b in question 5. Thomson effect is caused (A) due to both a and b (B) due to a but not due to b (C*) due to b but not due to a (D) neither due to a nor due to b iz'u la[;k 5 esa fn;s x;s dFkuksa a o b ij fopkj dhft;sA Fkkelu izHkko mRiUu gksrk gS (A) a o b nksuksa ds dkj.k (B) a ds dkj.k] fdUrq b ds dkj.k ugha (C*) u rks a ds dkj.k u gh b ds dkj.k (D) u rks a ds dkj.k u gh b ds dkj.k C Thomson effect is caused due to free electron density in a metal depends on temperature.
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Chapter # 33 Thermal and Chemical Effects of Electric Current 8. Faraday constant : (A) depends on the amount of the electrolyte (B) depends on the current in the electrolyte (C*) is a universal constant (D) depends on the amount of charge passed through the electrolyte. QSjkMs fu;rkad : (A) fo|qr vi?kV~; dh ek=kk ij fuHkZj djrk gSA (B) fo|qr vi?kV~; ls izokfgr /kkjk ij fuHkZj djrk gSA (C*) ,d lkoZf=kd fu;rkad gSA (D) fo|qr vi?kV~; ls izokfgr vkos'k dh ek=kk ij fuHkZj djrk gSA Sol. C Faraday constant is universal constant.
[3]
Objective - II 1.
Sol.
Two resistors having equal resistance are joined in series and current is passed through the combination. Negect any variation is resistance as the temperature changes. In a given time interval, (A*) equal amounts of thermal energy must be produced in the resistors (B) unequal amounts of thermal energy may be produced (C) the temperature must rise equally in the resistors (D*) the tepmerature may rise equally in the resistors
nks ,d leku izfrjks/k Js.khØe esa tksM+s x;s gSa rFkk bl la;kstu ls /kkjk izokfgr dh tk jgh gSA rki ifjorZu ds dkj.k izfrjks/k esa ifjorZu ux.; eku yhft;sA fdlh fuf'pr le;karjky esa (A*) izfrjks/k ij leku ek=kk esa m"ek ÅtkZ mRiUu gksxhA (B) izfrjks/kksa ij vleku ek=kk esa m"ek ÅtkZ mRiUu gksxhA (C) izfrjks/kksa esa fuf'pr :i ls leku rki o`f) gksxhA (D*) izfrjks/kksa esa rki o`f) leku gks ldrh gSA AD
R
R
I
H = I2Rt
2.
Sol.
Equal amount of thermal energy must be produced in the resistors. The temperature may rise equally in the resistors.
A copper strip AB and an iron strip AC are joined at A. The junction A is maintained at 0oC and the free ends B and C are maintained at 100oC. There is potential different between (A*) the two ends of the copper strip (B*) the copper end and the iron end at the junction (C*) the two ends of the iron strip (D*) the free ends B and C rkacs dh iV~Vh AB rFkk yksgs dh iV~Vh AC, A ij tqM+h gqbZ gSA laf/k A dk rki 0oC rFkk eqDr fljksa B o C dk rki 100oC fLFkj j[kk x;k gSA foHkokUrj gksxk (A*) rkacs dh iV~Vh ds nksuksa fljksa ds chp (B*) laf/k ij rkacs ds fljs rFkk yksgs ds fljs ds chp (C*) yksgs dh iV~Vh ds nksuksa fljksa ds chp (D*) eqDr fljksa B o C ds chp ABCD In steady state the rate of flow of that in both rods in the same.
Q Q t 1 t 2
K1A T1 T L1
B
K2 A T T2 L2
L1
K1 Copper T1=100°C
A
L2
C K2 Iron T2=100°C
“K, K2 is the conductivity of the metals.” So potential is different in different end (Because conductivity of metals are different)
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Chapter # 33 Thermal and Chemical Effects of Electric Current [4] 3. The constance a and b for the pair silver-lead are 2.50 V/oC and 0.012 V/o(C)2 respectively. For a silver-lead thermocouple with colder junction at 0oC, (A*) there will be no neutral temperature (B*) there will be no inversion temperature (C) there will not be any thermo-emf even if the junctions are kept at different temperatures (D) there will no current in the thermocouple even if the junction are kept at different temperature. pkanh rFkk lhls ds ;qXe ds fy;s fu;rkad a rFkk b ds eku Øe'k% 2.50 V/oC rFkk 0.012 V/o(C)2 gSA pkanh&lhlk rki&oS|qr ;qXe ftldh B.Mh laf/k dk rki 0oC gS] ds fy;s (A*) dksbZ mnklhu rki ugha gksxkA (B*) dksbZ O;qRØe.k rki ugha gksxkA (C) laf/k;ksa dks fHkUu&fHkUu rkiksa ij j[kus ij Hkh rki fo-ok-cy mRiUu ugha gksxkA (D) laf/k;ksa dks fHkUu&fHkUu rkiksa ij j[kus ij Hkh rki oS|qr ;qXe ls dksbZ /kkjk izokfgr ugha gksxhA Sol. AB There will be no neutral temperature. There will be no inversion temperature. 4.
Sol.
5.
Sol.
An electrolysis experiment is stopped and the battery terminals are reversed. (A) The electrolysis will stop (B) The rate of liberation of material at the electrodes will increased. (C*) The rate of liberation of material will remain the same (D) Heat will be produce at a greater rate ,d fo|qr&vi?kVu iz;ksx dks jksddj cSVjh ds VfeZuy iyV fn;s x;s gSa (A) fo|qr&vi?kVu :d tk;sxkA (B) bysDVªksMksa ij inkFkZ vo{ksfir gksus dh nj esa o`f) gks tk;sxhA (C*) inkFkZ vo{ksfir gksus dh nj ogh jgsxhA (D) m"ek mRiUu gksus dh nj esa o`f) gksxhA C An electrolysis experiment is stopped and the battery terminals are reversed. But the rate of liberation of meterial will remain the same. The electrochemical equivalent of a material depends on (A*) the nature of the material (B) the current through the electrolyte containing the material (C) the amount of charge passed through the electrolyte (D) the amount of this material present in the electrolyte. fdlh inkFkZ dk oS|qr&jklk;fud rqY;kad fuHkZj djrk gS (A*) inkFkZ dh izÑfr ij (B) inkFkZ dks j[kus okys fo|qr vi?kV~; dh izÑfr ij (C) fo|qr vi?kV~; ls izokfgr vkos'k ij (D) fo|qr vi?kV~; esa mifLFkr inkFkZ dh ek=kk ij A The electro chemical equivalent of a material depends on the nature of the material. Electro chemical equivalent of a substance is equal to its relative atomic mass divided by its valency.
