kak tolonglah, nomor 18 ama 19 . Pake caranya yah kak☺

Mapel : Fisika
Bab : Cermin dan Listrik statis

18) Cermin

s = 60 cm
f = 20 cm

1/f = 1/s' + 1/s
1/f - 1/s = 1/s'
1/20 - 1/60 = 1/s'
_______/60 = 1/s'
3/60 - 1/60 = 1/s'
2/60 = 1/s'
60/2 = s'
30 = s'

s' = 30 cm

M = |s'/s|
M = |30/60|
M = 1/2 kali

(D)

19. Listrik Statis

k × q1 × q2/r^2 = F
k × q^2/r^2 = F


F2 = k × 1/2q1 × 8q2/r^2
F2 = k × 4q^2/r^2
F2 = 4 k q^2/r^2
F2 = 4 F

(B)

18][ cermin cekung
f = 20 cm
s = 60 cm
m = __?

m = f / (s - f)
m = 20 / (60 - 20)
m = 20/40 = ½ kali ✔️


19][ gaya listrik
Q₁' = ½ Q₁
Q₂' = 8 Q₂
F' = __?

Gaya listrik
F = k Q₁ Q₂ / r²
F' = k Q₁' Q₂' / r²

perbandingan
F' / F = (Q₁' Q₂') / (Q₁ Q₂)
F' / F = (½Q₁ • 8Q₂) / (Q₁ Q₂)
F' / F = 4
F' = 4 F ✔️