Answer: Gravitational force
Explanation:
A non contact force can be described as a force applied to an object by another body that is not in direct contact with it.
For example, an object thrown upwards will return back due to the force of gravity acting on it. So, it means Gravitational force is acting on the body without necessarily being in contact with that body.
Answer:
add more coils
Explanation:
this increases the strength of the magnetic field
Answer:
Capacitive Reactance is 4 times of resistance
Solution:
As per the question:
R = 
where
R = resistance

f = fixed frequency
Now,
For a parallel plate capacitor, capacitance, C:

where
x = separation between the parallel plates
Thus
C ∝ 
Now, if the distance reduces to one-third:
Capacitance becomes 3 times of the initial capacitace, i.e., x' = 3x, then C' = 3C and hence Current, I becomes 3I.
Also,

Also,
Z ∝ I
Therefore,




Solving the above eqn:

Answer:
<h2>480</h2>
Explanation:
<h2>R=120÷0.25</h2><h2>R=480 ohms </h2>
because the unit for resistance is in ohms
Answer:
The frequencies are 
Explanation:
From the question we are told that
The length of the ear canal is 
The speed of sound is assumed to be 
Now taking look at a typical ear canal we see that we assume it is a closed pipe
Now the fundamental harmonics for the pipe(ear canal) is mathematically represented as

substituting values


Also the the second harmonic for the pipe (ear canal) is mathematically represented as
substituting values
Given that sound would be loudest in the pipe at the frequency, it implies that the child will have an increased audible sensitivity at this frequencies