They do the method 3 times to be sure. Because if you do it once, that could mean anything. If you do it twice, it may or may not have the same result. If you do it 3 times and it matches one of the previous answers, then it's likely that it's correct.
Answer:
proportional to the current in the wire and inversely proportional to the distance from the wire.
Explanation:
The magnetic field produced by a long, straight current-carrying wire is given by:
where
is the vacuum permeability
I is the current intensity in the wire
r is the distance from the wire
From the formula, we notice that:
- The magnitude of the magnetic field is directly proportional to I, the current
- The magnitude of the magnetic field is inversely proportional to the distance from the wire, r
Therefore, correct option is
proportional to the current in the wire and inversely proportional to the distance from the wire.
Strange as it may seem, the object would keep moving, in a straight line and at the same speed, until it came near another object. Its momentum and kinetic energy would never change. It might continue like that for a billion years or more.
Have a look at Newton's first law of motion.
Answer:
So then the difference of temperature across the material would be 
Explanation:
For this case we can use the Fourier Law of heat conduction given by the following equation:
(1)
Where k = thermal conductivity = 0.2 W/ mK
A= 1m^2 represent the cross sectional area
Q= 3KW represent the rate of heat transfer
is the temperature of difference that we want to find
represent the thickness of the material
If we solve 
in absolute value from the equation (1) we got:
First we convert 3KW to W and we got:
And we have everything to replace and we got:
So then the difference of temperature across the material would be
Answer: A volcanic island arc like Hawaii.
Explanation: The Hawaiian island is the most safest place for the people to live in comparison to the other given options.
The plate tectonic movement generates energy due to collision, resulting in sudden release of energy, and seismic waves are produced that propagates and causes earthquake.
Due to the constant collision between the plates, different places at different time experiences earthquake. Near a fault region, earthquakes are very severe, and also near the mid oceanic ridge it is not possible for a person to live. The subduction zones are the region where a denser plate subducts beneath the other, and its impossible for life to exist there.
Thus the most safest place out of all the option is the volcanic islands where numerous people resides. for example, the Hawaiian and Stromboli.
