Answer:
194 V/m
Explanation:
In order to find electric field, we can use the formula of power density
i.e Pd = E^2 / Z
where:
Pd = power density in W/m^2
E = electric field strength in V/m
Z = impedance of free space = 120 * π
E = sqrt(Pd * Z)
-----> re-arranging it for E
before solving, convert Pd unit into W/m^2
Pd= 5mW/cm^2 = 50 W/m^2
Solving for E:
E= sqrt(50 * 120 * π)
E = 137.3 V/m
the above value is RMS value
In order to find the peak amplitude of the oscillating field will therefore be 137.3 * sqrt(2) = 194 V/m
Exothermic is the right kind of reaction.
Answer:
A. F=107.6nN
B. Repulsive
Explanation:
According to coulombs law, the force between two charges is express as
F=(Kq1q2) /r^2
If the charges are of similar charge the force will be repulsive and if they are dislike charges, force will be attractive.
Note the constant K has a value 9*10^9
Hence for a charge q1=7.10nC=7.10*10^-9, q2=4.42*10^-9 and the distance r=1.62m
If we substitute values we have
F=[(9×10^9) ×(7.10×10^-9) ×(4.42×10^-9)] /(1.62^2)
F=(282.4×10^-9)/2.6244
F=107.6×10^-9N
F=107.6nN
B. Since the charges are both positive, the force is repulsive
The answer is C. Convection.
Radiation is the transfer of energy through electromagnetic waves. Conduction, on the other hand, is energy transfer through solid material. Condensation occurs when warm gas makes contact with a cold surface or environment, which causes a change in state from gas to liquid. These definitions rule out choices A, B, and D.
Convection is movement of particles in fluid or gas. As liquid/gas heats up, it becomes less dense and rises, moving away from the heat source. When it rises, it eventually cools down and sinks again. It is warmed up again and the cycle continues. This is why there is a circular motion when convection occurs.
