<span>A. The magnetic force increases.
F is inversely proportional to r</span>²<span>
Hope this helps!</span>
When the investigator wanted to reproduce the results with a beam of protons, the thing required is A. Lower speed particles than for the electron beam.
<h3>What is proton?</h3>
It should be noted that a proton simply means a stable subatomic particle that has a positive electric charge.
In this case, when the investigator wanted to reproduce the results with a beam of protons, the thing required is a lower speed particles than for the electron beam.
Learn more about protons on:
brainly.com/question/1805828
Explanation:
Formula to calculate the electric potential is as follows.

Putting the given values into the above formula as follows.

= ![\frac{9 \times 10^{9}}{0.25}[\frac{-3.3}{\sqrt{2}} + 4.2] \times 10^{-6}](https://tex.z-dn.net/?f=%5Cfrac%7B9%20%5Ctimes%2010%5E%7B9%7D%7D%7B0.25%7D%5B%5Cfrac%7B-3.3%7D%7B%5Csqrt%7B2%7D%7D%20%2B%204.2%5D%20%5Ctimes%2010%5E%7B-6%7D)
= 
Hence, electric potential at point A is
.
Now, the electric potential at point B is as follows.

= ![\frac{9 \times 10^{9}}{0.25} [-3.3 + \frac{4.2}{\sqrt{2}}] \times 10^{-6}](https://tex.z-dn.net/?f=%5Cfrac%7B9%20%5Ctimes%2010%5E%7B9%7D%7D%7B0.25%7D%20%5B-3.3%20%2B%20%5Cfrac%7B4.2%7D%7B%5Csqrt%7B2%7D%7D%5D%20%5Ctimes%2010%5E%7B-6%7D)
= 
Hence, electric potential at point B is
.
Answer:
A) 
Explanation:
Since a = g - bv,
We can substitute a = dv/dt into the equation.
Then, the equation will be like dv/dt = g - bv.
So we got first order differential equation.
As known, v = 0 at t = 0, and v = g/b at t = ∞.
Since
⇒ 
So take the integral of both side.

Since for t=0, v = 0 ⇒ 
