The electron is accelerated through a potential difference of

, so the kinetic energy gained by the electron is equal to its variation of electrical potential energy:

where
m is the electron mass
v is the final speed of the electron
e is the electron charge

is the potential difference
Re-arranging this equation, we can find the speed of the electron before entering the magnetic field:

Now the electron enters the magnetic field. The Lorentz force provides the centripetal force that keeps the electron in circular orbit:

where B is the intensity of the magnetic field and r is the orbital radius. Since the radius is r=25 cm=0.25 m, we can re-arrange this equation to find B:
The time constant determines how long it takes for the capacitor to charge.
To find the answer, we have to know more about the time constant of the capacitor.
<h3>What is time constant?</h3>
- The time it takes for a capacitor to discharge 36.8% of its charge in a discharging circuit or charge up to 63.2% of its maximum capacity in a charging circuit, given that it has no initial charge, is the time constant of a resistor-capacitor series combination.
- The circuit's reaction to a step-up (or constant) voltage input is likewise determined by the time constant.
- As a result, the time constant determines the circuit's cutoff frequency.
Thus, we can conclude that, the time constant determines how long it takes for the capacitor to charge.
Learn more about the time constant here:
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A: is potential
C: is losing kinetic energy and gaining potential energy
B: kinetic energy is at its highest
D: is loosing potential energy and gaining kinetic energy
You can only determine the speed since the only info we know is how much you ran in how long of a time.