The formular for determinatio of mass number is this:
Mass number = number of proton + number of neutron
From the question, we are told that:
Mass number = 39
Proton number = 19
Number of proton = ?
Number of neutron = mass number - number of proton
Number of neutron= 39 - 19 = 20
Therefore, number of neurtron = 20.
Answer:
0.25 m
Explanation:
Refraction occurs when the velocity or wavelength of a wave changes at the interface between two media.
We know that refractive index=
Wavelength in medium A/wavelength in medium B = velocity in medium A/velocity in medium B
Let the wavelength of medium B be a
0.5/a = 0.3/0.15
0.5 × 0.15 = 0.3 × a
a= 0.5 × 0.15/0.3
a= 0.25 m
Answer:
Part a)
![EMF = 14 \times 10^{-3} V](https://tex.z-dn.net/?f=EMF%20%3D%2014%20%5Ctimes%2010%5E%7B-3%7D%20V)
Part b)
![EMF = 15.67 \times 10^{-3} V](https://tex.z-dn.net/?f=EMF%20%3D%2015.67%20%5Ctimes%2010%5E%7B-3%7D%20V)
Explanation:
As we know that magnetic flux through the loop is given as
![\phi = B.A](https://tex.z-dn.net/?f=%5Cphi%20%3D%20B.A)
now we have
![\phi = B\pi r^2](https://tex.z-dn.net/?f=%5Cphi%20%3D%20B%5Cpi%20r%5E2)
now rate of change in flux is given as
![\frac{d\phi}{dt} = B(2\pi r)\frac{dr}{dt}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%5Cphi%7D%7Bdt%7D%20%3D%20B%282%5Cpi%20r%29%5Cfrac%7Bdr%7D%7Bdt%7D)
now we know that
![A = \pi r^2](https://tex.z-dn.net/?f=A%20%3D%20%5Cpi%20r%5E2)
![0.285 = \pi r^2](https://tex.z-dn.net/?f=0.285%20%3D%20%5Cpi%20r%5E2)
![r = 0.30 m](https://tex.z-dn.net/?f=r%20%3D%200.30%20m)
Now plug in all data
![EMF = (0.20)\times 2\pi\times (0.30) \times (0.037)](https://tex.z-dn.net/?f=EMF%20%3D%20%280.20%29%5Ctimes%202%5Cpi%5Ctimes%20%280.30%29%20%5Ctimes%20%280.037%29)
![EMF = 14 \times 10^{-3} V](https://tex.z-dn.net/?f=EMF%20%3D%2014%20%5Ctimes%2010%5E%7B-3%7D%20V)
Part b)
Now the radius of the loop after t = 1 s
![r_1 = r_0 + \frac{dr}{dt}](https://tex.z-dn.net/?f=r_1%20%3D%20r_0%20%2B%20%5Cfrac%7Bdr%7D%7Bdt%7D)
![r_1 = 0.30 + 0.037](https://tex.z-dn.net/?f=r_1%20%3D%200.30%20%2B%200.037)
![r_1 = 0.337 m](https://tex.z-dn.net/?f=r_1%20%3D%200.337%20m)
Now plug in data in above equation
![EMF = (0.20)\times 2\pi\times (0.337) \times (0.037)](https://tex.z-dn.net/?f=EMF%20%3D%20%280.20%29%5Ctimes%202%5Cpi%5Ctimes%20%280.337%29%20%5Ctimes%20%280.037%29)
![EMF = 15.67 \times 10^{-3} V](https://tex.z-dn.net/?f=EMF%20%3D%2015.67%20%5Ctimes%2010%5E%7B-3%7D%20V)
I believe the correct answer would be "A" energy source.