Zitsanzo za mafunso ndi njira zopezera mphamvu zamagetsi ndi mphamvu
Mphamvu ndi Mphamvu Zamagetsi
1. Mtengo wamagetsi pa kWh ndi Rp. 400. M'nyumba, TV ya 100 Watt imagwira ntchito kwa maola 4 patsiku, ndipo nyali ziwiri za 20 Watts zimagwiritsidwa ntchito kwa maola 10 patsiku. Mtengo wamagetsi wogwiritsidwa ntchito pamwezi (masiku 30) ndi….
A. Rp. 4.800,-
B. Rp. 9.600,-
C. Rp. 19.200,-
D. Rp. 21.120,-
Zokambirana
Amadziwika kuti:
Mtengo wamagetsi ndi Rp. 400/kWh
Mphamvu ya TV = 1 x 100 Watt = 100 Watt ndipo nthawi yogwiritsira ntchito TV = maola 4 x 30 = maola 120
Mphamvu ya nyali = 2 x 20 Watt = 40 Watt ndipo nthawi yogwiritsira ntchito nyali = maola 10 x 30 = maola 300
Anafunsa kuti: Mtengo wogwiritsira ntchito magetsi pamwezi
Yankho:
Mphamvu yamagetsi = mphamvu yamagetsi x nthawi yogwiritsira ntchito
Mphamvu yamagetsi ya TV = 100 Watt x maola 120 = maola 12.000 Watt
Mphamvu ya nyali = 40 Watt x maola 300 = maola 12.000 Watt
Mphamvu yonse = Maola 12.000 a Watt + Maola 12.000 a Watt = Maola 24 ...
Mtengo wogwiritsira ntchito magetsi pamwezi = (24 kWh)(Rp. 400/kWh) = (24)(Rp. 400) = Rp. 9.600,-
Yankho lolondola ndi B.
2. Nyali ziwiri, iliyonse yokhala ndi chizindikiro cha 24 Watt / 12 Volt, zimalumikizidwa motsatizana, kenako zimalumikizidwa motsatizana ndi choletsa cha 2 Ohm. Dera ili limalumikizidwa ku gwero la magetsi kuti nyali zonse ziwiri ziziwala ndi 25% yokha ya kuwala kwawo kwakukulu. Ngati nyali imodzi yasweka mwadzidzidzi, nyali inayo idzawala ndi mphamvu….
A. 12 Watts
B. 7,5 Watts
C. 6 Watts
D. 3 Watt
Zokambirana
Fomula ya mphamvu:
P = VI
Ine = PV
kapena
P = VI —–> I = V / R
P = V (V / R)
P=V2 / R
R = V2 /P
kapena
P = VI —–> V = IR
P = (IR) I
P = Ine2 R
I2 = P / R
Kufotokozera: P = mphamvu yamagetsi, V = magetsi amagetsi, I = magetsi amagetsi, R = kukana nyali
Kuwerengera kukana kwa dera:
Nyali ziwiri zilizonse zimalembedwa kuti 24 Watt / 12 Volt, zomwe zikutanthauza kuti nyali iliyonse imayatsa ndi mphamvu yayikulu ya 24 Watts ikalumikizidwa ku voteji ya 12 Volts.
Kukana kwa nyali iliyonse kumawerengedwa pogwiritsa ntchito njira yamagetsi:
R = V2 / P = 122 / 24 = 144 / 24 = 6 Ohms
Nyali ziwirizi zimalumikizidwa motsatizana kotero kukana kofanana ndi:
1 / R12 = 1/R1 + 1/R2 = 1/6 + 1/6 = 2/6
R12 = 6/2 = 3 Ohms
Nyali ziwirizi zimalumikizidwa motsatizana ndi chotsutsa cha 2 Ohm kotero kukana kofanana ndi:
R = 3 Ohm + 2 Ohm = 5 Ohm
Kotero kukana kwa dera = R = 5 Ohm.
Werengerani mphamvu yamagetsi yomwe ikuyenda mu dera:
Ngati magetsi onse awiri akuyaka ndi mulingo wowala wa 25% ndiye kuti magetsi onse awiri akuyaka ndi mphamvu ya 25/100 x 24 Watts = 1/4 x 24 = 24/4 = 6 Watts.
Mphamvu yamagetsi yomwe ikuyenda mu nyali imawerengedwa pogwiritsa ntchito njira yamagetsi:
I2 = P / R = 6 Watts / 6 Ohms = 1 Ampere
Mphamvu yamagetsi yomwe imayenda mu nyali iliyonse ndi 1 Ampere. Nyali ziwirizi zimalumikizidwa motsatizana, kotero malinga ndi lamulo loyamba la Kirchhoff, mphamvu yonse yamagetsi yomwe imayenda mu nyali zonse ziwiri ndi 2 Ampere. Nyali ziwirizi zimalumikizidwa motsatizana ndi choletsa cha 2 Ohm, kotero mphamvu yamagetsi yomwe imayenda mu choletsa cha 2 Ohm ndi 2 Ampere.
Kotero mphamvu yamagetsi yomwe ikuyenda mu dera = I = 2 Amperes.
Kuwerengera mphamvu ya magetsi ya gwero la emf:
Mphamvu yamagetsi ndi:
V = IR = (2 Ampere)(5 Ohm) = 10 Volts
Iyi ndi mphamvu ya magetsi ya gwero la EMF yomwe mtengo wake susintha nyali imodzi isanasweke kapena nyali imodzi itatha kusweka.
Werengerani kukana kwa dera pambuyo poti magetsi asweka:
Ngati magetsi amodzi asweka, magetsi ena omwe akadali kuyaka amalumikizidwa motsatizana ndi chotsutsa cha 2 Ohm. Chifukwa chake, kukana kwa dera kumasintha kukhala:
R = 6 Ohm + 2 Ohm = 8 Ohm
Werengerani mphamvu yamagetsi yomwe ikuyenda mu dera pambuyo poti magetsi amodzi asweka:
Mphamvu yamagetsi yomwe ikuyenda mu dera ndi iyi:
I = V / R = 10 Volts / 8 Ohms = 1,25 Amps
Nyali ndi choletsa magetsi zimalumikizidwa motsatizana kotero kuti mphamvu yamagetsi yomwe ikuyenda mu dera = mphamvu yamagetsi yomwe ikuyenda mu nyali = mphamvu yamagetsi yomwe ikuyenda mu choletsa magetsi.
Kuwerengera mphamvu ya nyali:
Magetsi ena akatha, magetsi ena amayaka ndi mphamvu ya:
P = VI = (10 Volt) (1,25 Ampere) = 12,5 Watt
Kuyenda kwa ma elekitironi
3. Kulemera kwa elekitironi kumadziwika kuti ndi 9,1 x 10-31 kg ndi mphamvu ya ma elekitironi 1,6 x 10-19 C. Kusiyana komwe kumafunika kuti electron ifulumizitse kuchokera pa liwiro la 1 x 105 m/s imakhala 3 x 105 m/s ndi….
A. 28,4375 mV
B. 56,875 mV
C. 113,75 mV
D. 227,5 mV
Zokambirana
Amadziwika kuti:
Kulemera kwa ma elekitironi (m) = 9,1 x 10-31 kg
Mphamvu ya ma elekitironi (q) = 1,6 x 10-19 C
Liwiro loyambirira (v)o) = 1 x 105 m/s —> vo2 = 1x10 pa10 m2/s2
Liwiro lomaliza (v)t) = 3 x 105 m/s —> vt2 = 9 x 1010 m2/s2
Anafunsa kuti: Kusiyana kwa kuthekera (V) komwe kumafunika kuti electron ifulumizitse
Yankho:
Kusintha kwa mphamvu zamagetsi = q V = (1,6 x 10-19 CV
Kusintha kwa mphamvu ya kinetic = EKt – EKo = 1/2 m (v)t2 -vo2) = 1/2 (9,1 x 10-31 kg)(9 x 1010 m2/s2 - 1 x 1010 m2/s2) = (4,55 x 10-31 kg)(8 x 1010 m2/s2) = 36,4 x 10-21 makilogalamu m2/s2
Mphamvu ndi yamuyaya kotero kuti mphamvu yamagetsi imasintha kukhala mphamvu ya kinetic:
EPL yatayika = EK yawonekera
(1,6x10-19) V = 36,4 x 10-21
V = 36,4 x 10-21 pa 1,6x10-19
V = 22,75 x 10-2 Volt
V = 227,5 x 10-3 Volt
V = 227,5 milliVolts
Yankho lolondola ndi D.
4. Mafunso a 2011 National Science Olympiad a Sukulu Zapamwamba pa Regency/Mzinda Nambala 56
Mu labotale, mtanda wa ma elekitironi umawomberedwa kumpoto. Kuchokera pamwamba, zimaoneka kuti mtandawo umakhota kumanzere. Kenako, mtanda wa ma elekitironi umawomberedwa kum'mwera. Kuchokera pamwamba, zimaoneka kuti mtandawo umakhota kumanzere. Izi zikutanthauza kuti pali…
A. malo amagetsi omwe aloza kumadzulo
B. malo amagetsi omwe aloza kum'mawa
C. mphamvu ya maginito yomwe imatsogozedwa mmwamba
D. mphamvu ya maginito yomwe imatsogozedwa pansi
Zokambirana
Ma electron amayendetsedwa ndi magetsi ndipo amatha kusunthidwa ndi mphamvu zamagetsi kapena maginito akakhala mu mphamvu zamagetsi kapena maginito. Kusiyana kwake ndi kwakuti mphamvu zamagetsi zimatha kusuntha ma electron onse akapuma komanso akamayenda, pomwe mphamvu zamagetsi zimatha kusuntha ma electron okha akamayenda.
Kusiyana kwina ndikuti mphamvu yamagetsi ili mbali imodzi ndi mphamvu yamagetsi, pomwe mphamvu yamagetsi ili mbali imodzi ndi mphamvu yamagetsi. Chifukwa chake, ngati elekitironi isunthidwa ndi mphamvu yamagetsi, njira yoyendera kwake ndi yofanana ndi njira ya mphamvu yamagetsi. Mosiyana ndi zimenezi, ngati elekitironi isunthidwa ndi mphamvu yamagetsi, njira yoyendera kwake ndi yofanana ndi njira ya mphamvu yamagetsi, yomwe ndi yolunjika ndi njira ya mphamvu yamagetsi.
Kutengera ndi funso lomwe lili pamwambapa, zikuwoneka kuti electron ikawomberedwa kumpoto, imapatutsidwa kumanzere (kumadzulo), ndipo ikawomberedwa kum'mwera, imapatutsidwa kumanzere (kum'mawa). Ngati electron ikawomberedwa ndi mphamvu yamagetsi, ndiye kuti njira ya mphamvu yamagetsi, yomwe ndi yofanana ndi njira ya mphamvu yamagetsi, nthawi zonse imasintha. Njira ya mphamvu yamagetsi iyenera kukhala yokhazikika. Chifukwa chake, electron sipatutsidwa ndi mphamvu yamagetsi.
Tinganene kuti mphamvu ya maginito imapotoza ma elekitironi. Kuti mudziwe komwe mphamvu ya maginito imalowera (kumene ma elekitironi amapotoza), komwe mphamvu ya maginito imalowera, ndi komwe ma elekitironi amawomberedwa, gwiritsani ntchito lamulo la dzanja lamanja.
Gwiritsani ntchito lamulo la dzanja lamanja monga tafotokozera pansipa. Tambasulani dzanja lanu lamanja, wongolerani chala chanu chachikulu ndikutseka zala zanu zina zinayi. Ikani chala chanu chachikulu kuti chiloze kumpoto (komwe kuli kayendedwe ka ma elekitironi) ndipo zala zanu zinayi ziloze kumadzulo (komwe kuli mphamvu ya maginito = komwe kuli kayendedwe ka ma elekitironi), kenako kumbuyo kwa dzanja lanu lamanja kudzaloza pansi (komwe kuli kayendedwe ka maginito). Mosiyana ndi zimenezi, ikani chala chanu chachikulu kuti chiloze kum'mwera (komwe kuli kayendedwe ka ma elekitironi) ndipo zala zanu zinayi zidzaloza kum'mawa (komwe kuli kayendedwe ka maginito = komwe kuli kayendedwe ka maginito), kenako kumbuyo kwa dzanja lanu lamanja kudzaloza pansi (komwe kuli kayendedwe ka maginito). Zingatsimikizidwe kuti elekitironi ili mu mphamvu ya maginito yomwe imayang'aniridwa pansi.
Yankho lolondola ndi D.
Gwero la funso:
Mafunso a OSN a Sukulu ya Sekondale ya Fiziki ya Sukulu ya Sekondale
