25 Malosiaga eletise – faʻafitauli ma fofo
1. O se moli eletise e 220 V – 5 e fa'aaogaina mo le 30 minute. O le a le tele o le malosiaga e mana'omia?
Fofo:
Voltage (V) = 220 Volt
Tafe eletise (I) = 5 Ampere
Taimi (t) = 30 minute = 30 x 60 sekone = 1800 sekone
Malosiaga eletise (P):
P = VI = (220 Volt)(5 Ampere) = 1100 Volt Ampere = 1100 Watt = 1100 Joule/sekona
Malosiaga eletise = Malosiaga eletise x taimi = (1100 Joule/sekone)(1800 sekone)
Malosiaga eletise = 1,980,000 Joules = 1,980 kiloJoules
2. E fa'aaogā se u'amea soldering e 220 V – 60 W mo le 4 minute. E fia le malosi e mana'omia.
Ua iloa:
Malosiaga (P) = 60 Watts = 60 Joules/sekone
Voltage (V) = 220 Volt
Taimi (t) = 4 minute = 4 x 60 sekone = 240 sekone
Manaomia: Malosiaga eletise
Fofo:
220 Volt – 60 Watt o lona uiga e lelei le galue o le solder eletise pe afai o le eseesega o le gafatia po'o le voltage e 220 volts ma e iai le malosiaga o le 60 Watt = 60 Joules/sekone, o lona uiga e fa'aogaina e le solder eletise le malosiaga o le 60 Joules i le sekone.
Malosiaga eletise = malosiaga eletise x vaitaimi va = (60 Joules/sekone)(240 sekone) = 14,400 Joules.
3. O le malosi e faʻaaogaina e le uʻamea mo le 1 minute e 33 kJ, i le voltage e 220 volts. O le tele o le tafe o loʻo i totonu o le uʻamea.
Ua iloa:
Vaitaimi va (t) = 1 minute = 60 sekone
Malosiaga (W) = 33 kiloJoules = 33,000 Joules
Voltage (V) = 220 Volt
Manaomia: Tafe eletise (I)
Fofo:
O le malosiaga eletise o le malosiaga eletise lea e faʻaaogaina i se vaitaimi patino.
P = W / t = 33,000 Joules / 60 sekone
P = 550 Uati
Tafe eletise:
I = P / V = 550 / 220 = 2.5 Amperes
4. E matamata se tasi i le TV i le averesi o le 6 itula i le aso. Ua fesoʻotaʻi le TV i le voltage 220 Volt o lea e tafe ai le eletise i le TV i le 0.5 Amperes. Afai e totogi e le kamupani eletise le $0.092 i le kWh, o le tau o le faʻaaogaina o le eletise mo le TV mo le 1 masina (30 aso) o le…
Ua iloa:
Vaitaimi = 6 itula x 30 = 180 itula
Voltage (V) = 220 Volt
Tafe eletise (I) = 0.5 Ampere
Manaomia: O le tau i le masina
Fofo:
Mana o le TV:
P = VI = (220 Volt)(0.5 Ampere) = 110 Volt Ampere = 110 Watt
Malosiaga eletise = malosiaga eletise x va o taimi
Malosiaga eletise o le TV = 110 Watt x 180 itula = 19800 Watt itula = 19.8 kilo Watt itula = 19.8 kilo Watt itula = 19.8 kWh
O le tau o le faʻaaogaina o le eletise mo le TV i le masina e tasi:
19.8 kWh x $0.092/kWh = $1.8216
5. I totonu o se fale e 4 moli e 20 Watt, 2 moli e 10 Watt, 3 moli e 40 Watt, e faʻaaogaina i le 5 itula i le aso. Afai o le totogi a le kamupani eletise e 0.092 i le kWh, o le tau o le faʻaaogaina o le eletise mo le 1 masina (30 aso) o le ….
Ua iloa:
4 moli 20 Watts = 4 x 20 Watts = 80 Watts
2 moli 10 Watts = 2 x 10 Watts = 20 Watts
3 moli 40 Watts = 3 x 40 Watts = 120 Watts
Malosiaga atoa (W) = 80 Watts + 20 Watts + 120 Watts = 220 Watts
Vaitaimi va (t) = 5 itula x 30 = 150 itula
Manaomia: O le tau o le faʻaaogaina o le eletise mo le 1 masina (30 aso)
Fofo:
Malosiaga eletise = malosiaga eletise x va o taimi = 220 Uati x 150 itula = 33,000 Uati itula = 33 kilokalama Uati itula = 33 kilokalama Uati itula = 33 kWh
O le tau o le faʻaaogaina o le eletise mo le 1 masina (30 aso)
(33 kWh)(0.092/kWh) = $3.036
6. O se matagaluega e iai le tete'e o le \(5\Omega\) ma le tafe o le \(2A\). Saili le malosiaga eletise.
Tali: \( P = IV = 2A \times 5\Omega = 10W \)
7. O lo'o fa'afeso'ota'i se maa \(10V\) i se resistor \(2\Omega\). Fa'atatau le tafe eletise.
Tali: \( I = \frac{V}{R} = \frac{10V}{2\Omega} = 5A \)
8. O se moli e fa'atulagaina i le \(60W\) e fa'agaoioia i se sapalai \(120V\). Saili le tete'e.
Tali: \( R = \frac{V^2}{P} = \frac{120^2}{60} = 240\Omega \)
9. Fuafua le malosi e fa'aaogaina e se moli uila \(100W\) i le \(2\) itula.
Tali: \( E = Pt = 100W \times 2h = 200Wh = 0.2kWh \)
10. O se capacitor \(20\mu F\) ua fa'atumuina i le \(50V\). Saili le malosiaga ua teuina.
Tali: \( E = \frac{1}{2} CV^2 = \frac{1}{2} \times 20 \times 10^{-6}F \times 50^2 = 25mJ \)
11. Fuafua le tafe o le eletise i totonu o se inductor \(10mH\) pe a o le fua faatatau o le suiga o le tafe o le eletise e \(5A/s\).
Tali: \( V = L\frac{di}{dt} = 10 \times 10^{-3}H \times 5A/s = 50mV \)
12. Saili le eletise ua leiloa i totonu o se laina fesiitaiga e iai le tete'e o le \(8\Omega\) ma le tafe o le \(3A\).
Tali: \( P = I^2R = 3^2 \times 8\Omega = 72W \)
13. O se transformer e iai le voltage muamua o le \(120V\) ma le voltage lona lua o le \(240V\). Afai o le tafe muamua o le \(2A\), saili le tafe lona lua.
Tali: Tafega lona lua = \( \frac{{\text{{Voltage muamua}}}}{{\text{{Voltage lona lua}}}} \times \text{{Tafega muamua}} = \frac{{120V}}{{240V}} \times 2A = 1A \)
14. Fuafua le tali atu (reactance) o se inductor (0.2H) (50Hz).
Tali: \(
15. Saili le aofa'i atoa o le capacitance o capacitors e tolu \(10\mu F\) ua feso'ota'i fa'asolosolo.
Tali: \( \frac{1}{{C_{\text{{total}}}} = \frac{1}{{C_1}} + \frac{1}{{C_2}} + \frac{1}{{C_3}} = \frac{1}{10} + \frac{1}{10} + \frac{1}{10} = \frac{3}{10}, C_{\text{{total}}} = \frac{10}{3} \mu F \approx 3.33\mu F \)
16. O se supercapacitor \(0.1F\) ua fa'atumuina i le \(5V\). Saili le malosiaga ua teuina.
Tali: \( E = \frac{1}{2} CV^2 = \frac{1}{2} \times 0.1 \times 5^2 = 1.25J \)
17. Fuafua le malosiaga o se matagaluega e iai le malosiaga moni o le \(60W\) ma le malosiaga vaaia o le \(75VA\).
Tali: Malosiaga o le malosiaga = \( \frac{{\text{{Malosiaga Moni}}}}{{\text{{Malosiaga Vaaia}}}} = \frac{{60W}}{{75VA}} \approx 0.8 \)
18. Saili le tete'e tutusa o ni tete'e se lua \(4\Omega\) o lo'o fa'atasi.
Tali: \( \frac{1}{{R_{\text{{eq}}}}} = \frac{1}{{R_1}} + \frac{1}{{R_2}} = \frac{1}{4} + \frac{1}{4} = \frac{1}{2}, R_{\text{{eq}}} = 2\Omega \)
19. Fuafua le impedance o se matagaluega e iai le tetee o le \(5\Omega\) ma le reactance o le \(12\Omega\).
Tali: \( Z = \sqrt{R^2 + X^2} = \sqrt{5^2 + 12^2} \approx 13.34\Omega \)
15. Fuafua le tau RMS o se voltage sinusoidal ma se tau pito i luga o le \(120V\).
Tali: \( V_{\text{{RMS}}} = \frac{{V_{\text{{tumutumu}}}}}{\sqrt{2}} \approx 84.85V \)
16. Saili le malosiaga ua fa'amamāina i totonu o se resistor \(5\Omega\) ma se tafega o le \(4A\).
Tali: \( P = I^2R = 4^2 \times 5\Omega = 80W \)
17. Fuafua le televave o se \(25mH\) inductor ma se reactance o le \(50\Omega\).
Tali: \( f = \frac{{X_L}}{{2\pi L}} = \frac{50}{{2\pi \times 25 \times 10^{-3}}} \approx 31.83Hz \)
18. Fuafua le tafe o le eletise i totonu o se tetee \(20\Omega\) faatasi ai ma se sapalai \(100V\).
Tali: \( I = \frac{V}{R} = \frac{100V}{20\Omega} = 5A \)
19. Saili le aofa'i atoa o le inductance o ni inductors se lua (10mH) ua feso'ota'i fa'atasi.
Tali: \( \frac{1}{{L_{\text{{total}}}}} = \frac{1}{{L_1}} + \frac{1}{{L_2}} = \frac{1}{10} + \frac{1}{10} = \frac{1}{5}, L_{\text{{total}}} = 5mH \)
20. Fuafua le malosi e fa'aaogaina e se u'amea \(1500W\) na fa'aaogaina mo le \(0.5\) itula.
Tali: \( E = Pt = 1500W \times 0.5h = 750Wh = 0.75kWh \)
