Answer:
The maximum speed of the ejected photoelectrons is 1.815 x 10⁶ m/s.
Explanation:
Given;
frequency of the light, f = 3.5 x 10¹⁵ Hz
work function of the metal, Φ = 5.11 eV
Φ = 5.11 x 1.602 x 10⁻¹⁹ J = 8.186 x 10⁻¹⁹ J
The energy of the incident light is given as sum of maximum kinetic energy and work function of the metal.
E = K.E + Φ
where;
E is the energy of the incident light, calculated as;
E = hf
E = (6.626 x 10⁻³⁴)(3.5 x 10¹⁵)
E = 2.319 x 10⁻¹⁸ J
The maximum kinetic energy of the photoelectrons is calculated as;
K.E = E - Φ
K.E = 2.319 x 10⁻¹⁸ J - 8.186 x 10⁻¹⁹ J
K.E = 2.319 x 10⁻¹⁸ J - 0.8186 x 10⁻¹⁸ J
K.E = 1.5004 x 10⁻¹⁸J
The maximum speed of the ejected photoelectrons in 10⁶ m/s is given as;
K.E = ¹/₂mv²

Therefore, the maximum speed of the ejected photon-electrons is 1.815 x 10⁶ m/s.
I honestly think it is B, if not I'm sorry for the incorrect answer, but B seems to be the only one to make sense
Charges or currents...... it could be either one hope it helps
Answer:
Explanation:
Given
half life
billion year
10 % to decay i.e. 90 % remaining
And 
where k= constant
t=time
and 
so 

t=0.684 billion year
(b)
t=13.8 billion year



atoms
Answer:
Zadanie 1. Przebyty dystans wynosi 800 m
Zadanie 2. Wykonana praca to 10 J
Zadanie 3. Zastosowana siła wynosi 500 N.
Explanation:
Zadanie 1. Oto mamy;
Równanie wykonanej pracy, W = siła, F × odległość, D przesunięte w kierunku siły
Gdzie:
W = 24 kJ
F = 30 N.
D = wymagany
W związku z tym;
W = F × D daje nam;
24 kJ = 24000 J = 30 N × D
Stąd D = 24000 J / (30 N) = 800 J / N = 800 metrów
Zadanie 2. Wykonana praca, W = F × D
Tutaj;
F = 50 N.
D = 20 cm = 0,2 m
∴ W = 50 N × 0,2 m = 10 J
Wykonana praca = 10 J
Zadanie 3. Oto mamy
Z równania wykonanej pracy W;
W = F × D
Ponieważ W = 3000 J
D = 6 m
Dlatego 3000 J = F × 6 m

Siła = 500 N.
Moc jest podana w następującym równaniu
Moc = (praca wykonana) / (czas poświęcony na pracę).