Answer:
(a) 
(b) 
Explanation:
(a) The surface current density of a conductor is the current flowing per unit length of the conductor.

Considering a wire, the current is uniformly distributed over the circumferenece of the wire.

The radius of the wire = a

The surface current density 
(b) The current density is inversely proportional
......(1)
k is the constant of proportionality

........(2)
substituting (1) into (2)





substitute 

Answer:
(a) ΔU=747J
(b) γ=1.3
Explanation:
For (a) change in internal energy
According to first law of thermodynamics the change in internal energy is given as
ΔU=Q-W
Substitute the given values
ΔU=970J-223J
ΔU=747J
For(b) γ for the gas.
We can calculate γ by ratio of heat capacities of the gas
γ=Cp/Cv
Where Cp is the molar heat capacity at constant pressure
Cv is the molar heat capacity at constant volume
To calculate γ we first need to find Cp and Cv
So
For Cp
As we know
Q=nCpΔT
Cp=(Q/nΔT)

From relation of Cv and Cp we know that
Cp=Cv+R
Where R is gas constant equals to 8.314J/mol.K
So

So
γ=Cp/Cv
γ=[(37J/mol.K) / (28.687J/mol.K)]
γ=1.3
When solar radiation reaches the Earth it quickly dissipates as most of the radiation and UV rays are blocked by ozone layer, but more radiation and UV rays are able to get through because of global warming.
Answer:
A police radar gun uses X-band microwave radiation at a frequency of 13.1 GHz. Microwaves travel at the speed of light, or 3x108 m/s. Since the frequency shift will be small for practical car speeds and difficult to detect, the shifted frequency is compared to the original frequency, and the resulting beat frequency is used to determine the speed of the car.
a.) If Michael is traveling at 29 m/s, what is the resulting beat frequency that the radar gun detects?
ANSWER: 2533 Hz
Explanation:
It’s c.) I think so at least