25 Ikehu uila - nā pilikia a me nā hoʻonā
1. Hoʻohana ʻia ke kukui uila he 220 V – 5 no 30 mau minuke. ʻEhia ka nui o ka ikehu e pono ai?
Lōlā:
Uila uila (V) = 220 Volt
Au uila (I) = 5 Ampere
Manawa (t) = 30 minuke = 30 x 60 kekona = 1800 kekona
Mana uila (P):
P = VI = (220 Volt)(5 Ampere) = 1100 Volt Ampere = 1100 Watt = 1100 Joule/kekona
Ikehu uila = Mana uila x manawa = (1100 Joule/kekona)(1800 kekona)
Ikehu uila = 1,980,000 Joules = 1,980 kiloJoules
2. Hoʻohana ʻia kahi hao soldering 220 V - 60 W no 4 mau minuke. ʻEhia ka nui o ka ikehu e pono ai.
ʻIke ʻia:
Mana (P) = 60 Watts = 60 Joules/kekona
Uila uila (V) = 220 Volt
Manawa (t) = 4 minuke = 4 x 60 kekona = 240 kekona
Makemake ʻia: Mana uila
Lōlā:
ʻO ke ʻano o 220 Volt – 60 Watt, hana maikaʻi ka solder uila inā he 220 volts ka ʻokoʻa hiki a i ʻole ka volta a he 60 Watt ka mana = 60 Joules/kekona, ʻo ia hoʻi, hoʻohana ka solder uila i ka ikehu o 60 Joules i kekona.
Ikehu uila = mana uila x ka manawa = (60 Joules/kekona)(240 kekona) = 14,400 Joules.
3. ʻO ka ikehu i hoʻohana ʻia e ka hao no 1 minuke he 33 kJ, ma kahi uila o 220 volts. Pehea ka nui o ke au i loko o ka hao.
ʻIke ʻia:
Ka manawa (t) = 1 minuke = 60 kekona
Ikelika (W) = 33 kiloJoules = 33,000 Joules
Uila uila (V) = 220 Volt
Makemake ʻia: Au uila (I)
Lōlā:
ʻO ka mana uila ka ikehu uila i hoʻohana ʻia i loko o kahi manawa kikoʻī.
P = W / t = 33,000 Joules / 60 kekona
P = 550 Watt
Au uila:
ʻO I = P / V = 550 / 220 = 2.5 Amperes
4. Nānā kekahi i ke TV ma ka awelika he 6 mau hola i ka lā. Hoʻopili ʻia ke TV i kahi uila 220 Volt i mea e kahe ai ke au uila ma o ke TV he 0.5 Amperes. Inā uku ka ʻoihana uila he $0.092 no kWh, a laila ʻo ke kumukūʻai o ka hoʻohana ʻana i ka ikehu uila no ke TV no 1 mahina (30 mau lā) he…
ʻIke ʻia:
Ka manawa = 6 hola x 30 = 180 hola
Uila uila (V) = 220 Volt
Au uila (I) = 0.5 Ampere
Makemake ʻia: Ke kumukūʻai no kēlā me kēia mahina
Lōlā:
Mana o ke kīwī:
P = VI = (220 Volt)(0.5 Ampere) = 110 Volt Ampere = 110 Watt
Ikehu uila = mana uila x ka wā manawa
Ikehu uila o ke TV = 110 Watt x 180 hola = 19800 Watt hola = 19.8 kilo Watt hola = 19.8 kilo Watt hola = 19.8 kWh
ʻO ke kumukūʻai o ka hoʻohana ʻana i ka ikehu uila no ke TV no 1 mahina:
19.8 kWh x $0.092/kWh = $1.8216
5. I loko o kahi hale, aia he 4 mau kukui 20 Watt, 2 mau kukui 10 Watt, 3 mau kukui 40 Watt, e hoʻohana ʻia ana no 5 mau hola i kēlā me kēia lā. Inā he 0.092 no kWh ka uku o ka ʻoihana uila, a laila ʻo ke kumukūʻai o ka hoʻohana ʻana i ka ikehu uila no 1 mahina (30 mau lā) he ….
ʻIke ʻia:
4 mau kukui 20 Watts = 4 x 20 Watts = 80 Watts
2 mau kukui 10 Watts = 2 x 10 Watts = 20 Watts
3 mau kukui 40 Watts = 3 x 40 Watts = 120 Watts
Ka mana holoʻokoʻa (W) = 80 Watts + 20 Watts + 120 Watts = 220 Watts
Ka manawa (t) = 5 hola x 30 = 150 hola
Makemake ʻia: Ke kumukūʻai o ka hoʻohana ʻana i ka ikehu uila no 1 mahina (30 lā)
Lōlā:
Ikehu uila = mana uila x ka manawa = 220 Watt x 150 hola = 33,000 Watt hola = 33 kilo Watt hola = 33 kilo Watt hola = 33 kWh
ʻO ke kumukūʻai o ka hoʻohana ʻana i ka ikehu uila no 1 mahina (30 lā)
(33 kWh)(0.092/kWh) = $3.036
6. He kū'ē ko kekahi kaapuni o \(5\Omega\) a he au o \(2A\). E huli i ka mana uila.
Hoʻonā: \( P = IV = 2A \times 5\Omega = 10W \)
7. Ua hoʻopili ʻia kahi pākahiko \(10V\) i kahi resistor \(2\Omega\). E helu i ke au.
Hoʻonā: \( I = \frac{V}{R} = \frac{10V}{2\Omega} = 5A \)
8. Hana kahi kukui uila i helu ʻia ma \(60W\) ma kahi lako \(120V\). E huli i ke kū'ē.
Hoʻonā: \( R = \frac{V^2}{P} = \frac{120^2}{60} = 240\Omega \)
9. E helu i ka ikehu i hoʻopau ʻia e kahi kukui \(100W\) i loko o \(2\) mau hola.
Hoʻonā: \( E = Pt = 100W \times 2h = 200Wh = 0.2kWh \)
10. Hoʻopiʻi ʻia kahi capacitor \(20\mu F\) i \(50V\). E huli i ka ikehu i mālama ʻia.
Hoʻonā: \( E = \frac{1}{2} CV^2 = \frac{1}{2} \times 20 \times 10^{-6}F \times 50^2 = 25mJ \)
11. E hoʻoholo i ke au i loko o kahi inductor \(10mH\) ke ʻo ka wikiwiki o ka loli o ke au he \(5A/s\).
Hoʻonā: \( V = L\frac{di}{dt} = 10 \times 10^{-3}H \times 5A/s = 50mV \)
12. E huli i ka pohō mana i loko o kahi laina hoʻoili me ke kū'ē o \(8\Omega\) a me ke au o \(3A\).
Hoʻonā: \( P = I^2R = 3^2 \times 8\Omega = 72W \)
13. He volta mua ko ka mea hoʻololi uila o \(120V\) a he volta lua o \(240V\). Inā ʻo ke au mua ʻo \(2A\), e ʻimi i ke au lua.
Hoʻonā: Au lua = \( \frac{{\text{{Au uila mua}}}}{{\text{{Au uila lua}}}} \times \text{{Au uila mua}} = \frac{{120V}}{{240V}} \times 2A = 1A \)
14. E helu i ka reactance o kahi inductor \(50Hz\), \(0.2H\).
Hoʻonā: \(
15. E huli i ka capacitance holoʻokoʻa o ʻekolu mau capacitors \(10\mu F\) i hoʻopili ʻia ma ke ʻano moʻo.
Hoʻonā: \( \frac{1}{{C_{\text{{total}}}} = \frac{1}{{C_1}} + \frac{1}{{C_2}} + \frac{1}{{C_3}} = \frac{1}{10} + \frac{1}{10} + \frac{1}{10} = \frac{3}{10}, C_{\text{{total}}} = \frac{10}{3} \mu F \approx 3.33\mu F \)
16. Hoʻopiʻi ʻia kahi supercapacitor \(0.1F\) i \(5V\). E huli i ka ikehu i mālama ʻia.
Hoʻonā: \( E = \frac{1}{2} CV^2 = \frac{1}{2} \times 0.1 \times 5^2 = 1.25J \)
17. E helu i ka mana o kahi kaapuni me ka mana maoli o \(60W\) a me ka mana i ʻike ʻia o \(75VA\).
Hoʻonā: Mana kumu = \( \frac{{\text{{Mana Maoli}}}}{{\text{{Mana ʻIke ʻia}}}} = \frac{{60W}}{{75VA}} \approx 0.8 \)
18. E huli i ke kū'ē like o ʻelua mau resistors \(4\Omega\) ma ke ʻano like.
Hoʻonā: \( \frac{1}{{R_{\text{{eq}}}}} = \frac{1}{{R_1}} + \frac{1}{{R_2}} = \frac{1}{4} + \frac{1}{4} = \frac{1}{2}, R_{\text{{eq}}} = 2\Omega \)
19. E hoʻoholo i ka impedance o kahi kaapuni me ke kū'ē o \(5\Omega\) a me ka reactance o \(12\Omega\).
Hoʻonā: \( Z = \sqrt{R^2 + X^2} = \sqrt{5^2 + 12^2} \approx 13.34\Omega \)
15. E helu i ka waiwai RMS o kahi voltage sinusoidal me ka waiwai kiʻekiʻe o \(120V\).
Hoʻonā: \( V_{\text{{RMS}}} = \frac{{V_{\text{{peak}}}}}{\sqrt{2}} \approx 84.85V \)
16. E huli i ka mana i hoʻopau ʻia i loko o kahi resistor \(5\Omega\) me ke au o \(4A\).
Hoʻonā: \( P = I^2R = 4^2 \times 5\Omega = 80W \)
17. E helu i ke alapine (frequency) o kahi inductor \(25mH\) me ka reactance o \(50\Omega\).
Hoʻonā: \( f = \frac{{X_L}}{{2\pi L}} = \frac{50}{{2\pi \times 25 \times 10^{-3}}} \approx 31.83Hz \)
18. E hoʻoholo i ke au i loko o kahi resistor \(20\Omega\) me kahi lako \(100V\).
Hoʻonā: \( I = \frac{V}{R} = \frac{100V}{20\Omega} = 5A \)
19. E huli i ka inductance holoʻokoʻa o ʻelua mau inductors \(10mH\) i hoʻopili ʻia ma ke ʻano like.
Hoʻonā: \( \frac{1}{{L_{\text{{total}}}}} = \frac{1}{{L_1}} + \frac{1}{{L_2}} = \frac{1}{10} + \frac{1}{10} = \frac{1}{5}, L_{\text{{total}}} = 5mH \)
20. E helu i ka ikehu i hoʻopau ʻia e kahi hao \(1500W\) i hoʻohana ʻia no \(0.5\) mau hola.
Hoʻonā: \( E = Pt = 1500W \times 0.5h = 750Wh = 0.75kWh \)
