Answer:
2583.9 N/C
Explanation:
Parameters given:
Outer diameter = 14 cm
Outer radius, R = 7cm = 0.07m
Inner diameter = 7 cm
Inner radius, r = 3.5 cm = 0.035m
Charge of washer = 8 nC = 8 * 10^(-9)C
Distance from washer, z = 33 cm = 0.33m
The electric field due to a washer (hollow disk) is given as:
E = k * σ * 2π [ 1 - z/(√(z² + R²)]
Where σ = charge per unit area
σ = q/π(R² - r²)
σ = 8 * 10^(-9) /(π*(0.07 - 0.035)²)
σ = 2.077 * 10^(-6) C/m²
=> E = 9 * 10^9 * 2.077 * 10^(-6) * 2π * [1 - 0.33/(√(0.33² + 0.07²)]
E = 117.467 * 10^3 * (1 - 0.978)
E = 117.467 * 10^3 * 0.022
E = 2583.9 N/C
Answer:
the decay of half of the nuclei only a half-life has passed
, b) in rock time it is 1 108 years
Explanation:
The radioactive decay is given by
N = N₀ 
If half of the atoms have decayed
½ N₀ = N₀
½ =
₀
Ln 0.5 = - λ t
t = - ln 0.5 /λ
The definition of average life time is
= ln 2 / λ
λ = ln 2 /
λ = 0.693 / 100 10⁶
λ = 0.693 10⁻⁸ years
We replace
t = -ln 0.5 / 0.693 10⁻⁸
t = 10⁸ years
We see that for the decay of half of the nuclei only a half-life has passed
b) in rock time it is 1 108 years
Have you ever looked up the density of a substance ? You ought to try it. Go ahead. Pick a substance, then go online or open up an actual book and find its density. You will never see any particular volume mentioned along with the density . . . because it doesn't matter. The whole idea of density is that it describes the substance, no matter how much or how little you have of it. The density of a tiny drop of water under a microscope is the same as the density of a supertanker-ful of water.
