In order to calculate the thermal energy, first let's calculate the power, using the formula:
For a voltage V = 9 Volts and a resistance R = 50 ohms, we have:
Now, multiplying the power by the time (in seconds), we can find the energy:
In scientific notation, we have an energy of 7.3 * 10^2 J, therefore the correct option is the fourth one.
A) 1.55
The speed of light in a medium is given by:
where
is the speed of light in a vacuum
n is the refractive index of the material
In this problem, the speed of light in quartz is
So we can re-arrange the previous formula to find n, the index of refraction of quartz:
B) 550.3 nm
The relationship between the wavelength of the light in air and in quartz is
where
is the wavelenght in quartz
is the wavelength in air
n is the refractive index
For the light in this problem, we have
Therefore, we can re-arrange the equation to find , the wavelength in air: