Answer: The magnetic flux density at a distance of 20 cm from the moving charge is 2.5x10^-9 T
Step-by-step explanation:
To calculate the magnetic flux density, we need to use the formula for the magnetic field created by a moving charge:

where:
B is the magnetic flux density
is the vacuum permeability constant
q is the charge of the moving charge (in coulombs)
v is the velocity of the moving charge (in m/s)
r is the distance from the moving charge (in meters)
In this problem, we have:
q = 3x10⁴ C (the rate at which the electric charge moves per minute)
v = ?
r = 0.2 m = 20 cm
To find the velocity (v), we need to convert the rate of electric charge to a current.
∴

where I is the electric current (in amperes) and t is the time (in seconds).
Since the rate is given in coulombs per minute, we need to convert the time to seconds:
t = 1 minute = 60 seconds
∴ I = q / t = (3x10^-4 C) / (60 s) = 5x10^-6 A
Now we can use the formula for the magnetic flux density:

Putting the values, we get:

Simplifying, we get:
v = B * 2 * 10^3 m/s
Dividing both sides by 2*10^3 m/s, we get:
B = v / (2 * 10^3 m/s)
Plugging in the value of v, we get:
B = 5x10^-6 A / (2 * 10^3 m/s) = 2.5x10^-9 T
Therefore, the magnetic flux density at a distance of 20 cm from the moving charge is 2.5x10^-9 T.