Answer:

Explanation:
q = Charge in the potassium ion = 
e = Charge of electron = 
= Change in potential = 
Change in electric potential is given by

The energy is 
The derived unit for voltage is named volt.
Answer:
Magnetic field, B = 0.88 T
Explanation:
It is given that,
The dimension of rectangular surface is 2.80 cm by 3.15 cm. The area of rectangular surface is, 
Angle between the uniform magnetic field and the horizontal, 
Magnetic flux, 
Let B is the magnitude of magnetic field in which the rectangular surface is placed. It is given by :

is the angle between magnetic field and the area
Here, 


B = 0.88 T
So, the magnitude of magnetic field is 0.88 T. Hence, this is the required solution.
The given question is incomplete. The complete question is attached with an image below.
Explanation:
Mass flow rate through region A will be calculated as follows.
Rate = 
= 
= 
= 
Therefore, we can conclude that the mass flow rate through region A is
.