N₀ = number of radioactive atoms initially present = 128
N = number of radioactive atoms left after time "t" = 2
t = time taken
T = half life period for the radioactive metal = 20 years
λ = decay constant = ?
decay constant is given as
λ = 0.693/T
inserting the values
λ = 0.693/20
λ = 0.0347
number of radioactive atoms left after time "t" is given as
N = N₀
inserting the values
2 = (128)
t = 120 years
Explanation:
<h2>Interference is the example of soap bubble colouring</h2>
<h3>EXTRA INFO:</h3>
(LOOK AT THE IMAGE)
An incoming light ray is partly reflected by the top surface of the soap film and partly reflected by the bottom surface. The wave reflected from the bottom surface has traveled further (an extra distance equal to twice the thickness of the film) so emerges out of step with the top wave. When the two waves meet, they add together, and some colors are removed by destructive interference. Where the film is thickest, the bubble appears more blueish; where it's thinner, it will look more violet or magenta.
Answer:
Time taken by car to cover 10m is 5.42 seconds and final velocity is 0m/s.