Question

Gambar berikut menunjukkan tiga buah lampu menyala selama 5 menit. Energi listrik yang diperlukan adalah...
a. 18.000 j
b. 27.000 j
c. 45.000 j
d. 54.000 j

tolong jawaban dan cara mengerjakannya

Answer 1

Dik : I = 3A
R :
1/Rp = 1/20 + 1/30 + 1/60
1/Rp = 3+2+1/60
1/Rp = 6/60
Rp = 60/6 = 10 ohm
t = 5 menit = 5 x 60 = 300 s
Jawab : W = I^2.R.t
= 9.10.300
= 27000 Joule ( b )

Answer 2

1/Rp = 1/R₁ + 1/R₂ + 1/R₃
Rp = (1/R₁ + 1/R₂ + 1/R₃)⁻¹
      = (1/20 + 1/30 + 1/60)⁻¹
      = (1/10)⁻¹ = 10 Ω

E = Pt
E = VIt
E = I²Rp t
    = (3)²(10)(300) = 27000 J
Jawaban: B.