Answer:
1 * 10^-7 [J]
Explanation:
To solve this problem we must use dimensional analysis.
1 ergos [erg] is equal to 1 * 10^-7 Joules [J]
![1[erg]*\frac{1*10^{-7} }{1}*[\frac{J}{erg} ] \\= 1*10^{-7}[J]](https://tex.z-dn.net/?f=1%5Berg%5D%2A%5Cfrac%7B1%2A10%5E%7B-7%7D%20%7D%7B1%7D%2A%5B%5Cfrac%7BJ%7D%7Berg%7D%20%5D%20%5C%5C%3D%201%2A10%5E%7B-7%7D%5BJ%5D)
Answer:
55407
Explanation:
we have given that magnetic field B=3.5 T
current through the coil=90 A
Length of solenoid =0.72 m
we know the formula of magnetic field

so 
so the number of turn in solenoid will be 55407
Answer:
Ultraviolet radiation would yield more electrical energy
Explanation:
The reason for the ultraviolet to generate more energy is that there would be getting more electrons per unit of time the photovoltaic cell, due to the higher frequency of the ultraviolet in comparison with the infrared radiation.
The infrared spectrum goes from 300 GHz (10^9 Hertz) to 400 THz or (10^12 Hertz).
The ultraviolet spectrum goes from 800 THz to 30.000 THz or (10^12 Hertz). This kind of radiation is responsible for skin burn from the sun and it´s the “ most usable” part from the sunlight in a photovoltaic cell.
The speed of sound at

is approximately v=343 m/s. The distance covered by the sound wave is

And the time it takes is

Now we want to find how far the light travels during this time. Light travels at speed

, therefore the distance it covers during this time is