Answer: 71.72 days
Explanation:
This problem can be solved using the <u>Radioactive Half Life Formula: </u>
(1)
Where:
is the final amount of Iodine-131
is the initial amount of Iodine-131
is the time elapsed
is the half life of Iodine-131
Knowing this, let's substitute the values and find from (1):
(2)
(3)
Applying natural logarithm in both sides:
(4)
(5)
Finding :
Answer:
B = - 1.51 10⁻⁷ T
Explanation:
For this exercise we can use Faraday's law of induction
E = -
In this case, they indicate that the normal and the magnetite field are in the same direction, so the angle is zero (cos 0 = 1), they give the area of the loop A = 4.32 10⁻⁴ m² and since we have N = 1470 turns in each one a voltage is induced
E = - N B A
B = -E A / N (1)
we find the induced voltage with ohm's law
V = i R
where the current is defined by
i = Q / t
we substitute
V = Q R / t
let's calculate
V = 9.18 10-3 56.0 / t
We must assume a time normally is t = 1 s
V = 0.514 V
this is the voltage in the circuit which must be the induced voltage V = E
we substitute in 1
B = - 0.514 4.32 10⁻⁴ / 1470
B = - 1.51 10⁻⁷ T