Answer:
The distance from the radio station is 0.28 light years away.
Solution:
As per the question:
Distance, d = 4 ly
Frequency of the radio station, f = 854 kHz = 
Power, P = 50 kW = 
Now,
From the relation:
P = nhf
where
n = no. of photons/second
h = Planck's constant
f = frequency
Now,
Area of the sphere, A = 
Now,
Suppose the distance from the radio station be 'r' from where the intensity of the photon is 
Now,
We know that:
1 ly = 
Thus
Answer: A) highly mobile electrons in the valence shell
Explanation: conductivity in metals is a result of the movement of electrically charged particles—the electrons. These free electrons also known as valence electrons are free to move, and as a result they can travel through the lattice that forms the physical structure of a metal. The presence of valence electrons determines a metal's conductivity. However, several other factors can affect the conductivity of a metal such as impurities, temperature, magnetic fields etc.
Answer:
T = 37.08 [N*m]
Explanation:
We must remember that torque is defined as the product of a force by a distance. This distance is measured from the point of application of force to the center of rotation of the rotating body.
The force is equal to the product of mass by gravitational acceleration.
![F=m*g\\F=70*9.81\\F=686.7[N]](https://tex.z-dn.net/?f=F%3Dm%2Ag%5C%5CF%3D70%2A9.81%5C%5CF%3D686.7%5BN%5D)
Now the torque can be calculated:
![T=F*r\\T=686.7*0.054\\T=37.08[N*m]](https://tex.z-dn.net/?f=T%3DF%2Ar%5C%5CT%3D686.7%2A0.054%5C%5CT%3D37.08%5BN%2Am%5D)
I am not sure but i think the answer is C
Well, the thing is: we don't really know, as we don't even know how many species there are on earth.
If we take a look at the estimates of <span>World Wide Fund for Nature, an organization that works toward combating species extinction, their estimates vary from 200 to 100 000 - but a probable number is 20 000 (d). </span>
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