Answer:
1)
2) ![E=0.037 \: V/m](https://tex.z-dn.net/?f=E%3D0.037%20%5C%3A%20V%2Fm)
Explanation:
1)
The intensity equation is given by:
![I=\frac{P}{4\pi r^{2}}](https://tex.z-dn.net/?f=I%3D%5Cfrac%7BP%7D%7B4%5Cpi%20r%5E%7B2%7D%7D)
Where:
- P is the power of the radio wave
- r is the distance from the source
![I=\frac{20000}{4\pi (30000)^{2}}](https://tex.z-dn.net/?f=I%3D%5Cfrac%7B20000%7D%7B4%5Cpi%20%2830000%29%5E%7B2%7D%7D)
2)
Now, the intensity and the electric field are related as:
![I=0.5c\epsilon_{0}E^{2}](https://tex.z-dn.net/?f=%20I%3D0.5c%5Cepsilon_%7B0%7DE%5E%7B2%7D)
Here:
- c is the speed of light
- ε₀ is the electric permittivity
- E is the electric field
We need to solve it for E.
![E= \sqrt{\frac{2I}{c\epsilon_{0}}}](https://tex.z-dn.net/?f=E%3D%20%5Csqrt%7B%5Cfrac%7B2I%7D%7Bc%5Cepsilon_%7B0%7D%7D%7D)
![E= \sqrt{\frac{2(1.8*10^{-6})}{(3*10^{8})(8.85*10^{-12})}}](https://tex.z-dn.net/?f=E%3D%20%5Csqrt%7B%5Cfrac%7B2%281.8%2A10%5E%7B-6%7D%29%7D%7B%283%2A10%5E%7B8%7D%29%288.85%2A10%5E%7B-12%7D%29%7D%7D)
![E=0.037 \: V/m](https://tex.z-dn.net/?f=E%3D0.037%20%5C%3A%20V%2Fm)
I hope it helps you!
Answer:
B) T > ma.
Explanation:
To solve this problem, we have to analyze the forces acting in the horizontal direction.
In the horizontal direction, we have:
- The horizontal component of the tension in the wire,
, where T is the magnitude of the tension and
the angle that the wire makes with the horizontal
Since this is the only force acting on the box in the horizontal direction, this is also the net force, so it is equal to the product of mass and acceleration (Newton's second law of motion):
![Tcos \theta = ma](https://tex.z-dn.net/?f=Tcos%20%5Ctheta%20%3D%20ma)
where
m is the mass of the box
a is the acceleration
We can rewrite the equation as
![T=\frac{ma}{cos \theta}](https://tex.z-dn.net/?f=T%3D%5Cfrac%7Bma%7D%7Bcos%20%5Ctheta%7D)
The angle in this problem is
, so
![T=\frac{ma}{cos 15^{\circ}}=\frac{ma}{0.966}=1.035 ma](https://tex.z-dn.net/?f=T%3D%5Cfrac%7Bma%7D%7Bcos%2015%5E%7B%5Ccirc%7D%7D%3D%5Cfrac%7Bma%7D%7B0.966%7D%3D1.035%20ma)
Therefore, the correct option is
B) T > ma.
Series circuits - cpt connected so that the same current passes through each of them.
Disconnection/break in series circuit and current doesn't flow.
Current same
The total potential difference across all of the components. (the sum of the pds across the individual series elements).
The diagram in the enclosure seems to show resistors in parallel. Which is a bit confusing ...
If you look at the units of density, g/cm^3 you will see it's grams divided by volume (cm^3).
218.9 g / (0.5*1.55*25 cm^3) = 11.3 g/cm^3