Speed of wave is given as

Wavelength of the wave is given as

now from the formula of wave time period we can say




so it will have time period of T = 4 s
Answer:
(a) B = 2.85 ×
Tesla
(b) I = I = 0.285 A
Explanation:
a. The strength of magnetic field, B, in a solenoid is determined by;
r = 
⇒ B = 
Where: r is the radius, m is the mass of the electron, v is its velocity, q is the charge on the electron and B is the magnetic field
B = 
= 
B = 2.85 ×
Tesla
b. Given that; N/L = 25 turns per centimetre, then the current, I, can be determined by;
B = μ I N/L
⇒ I = B ÷ μN/L
where B is the magnetic field, μ is the permeability of free space = 4.0 ×
Tm/A, N/L is the number of turns per length.
I = B ÷ μN/L
= 
I = 0.285 A
Explanation:
The newton's laws of motion are:
First law:
"A body will remain in its state of rest or of uniform motion along a path unless it is acted upon by an external force. ".
This is popularly called the law of inertia.
Second law:
"the acceleration of a body is produced by a net force that is inversely proportional to the mass of the body".
Third law:
"action and reaction forces are equal and opposite in direction".
learn more:
Newton's laws brainly.com/question/11411375
#learnwithBrainly
We have no idea. There are probably many things involved ... the planet's mass,
the availability of small bodies in the neighborhood that can be captured, etc.