An electron moves in the direction of a uniform electric field. Its initial speed is5.00 × 106 m s−1 and stops momentarily after moving through a distance of 20.0 cm.(a) What is the strength of the electric field?(b) Why the electron stops momentarily?
Question
An electron moves in the direction of a uniform electric field. Its initial speed is5.00 × 106 m s−1 and stops momentarily after moving through a distance of 20.0 cm.(a) What is the strength of the electric field?(b) Why the electron stops momentarily?
Solution
(a) To find the strength of the electric field, we first need to find the acceleration of the electron. We know that the electron comes to a stop, so its final velocity is 0 m/s. We can use the equation v^2 = u^2 + 2as, where v is the final velocity, u is the initial velocity, a is the acceleration, and s is the distance.
Rearranging for a gives a = (v^2 - u^2) / (2s). Substituting the given values gives a = (0 - (5.00 × 10^6)^2) / (2 * 0.20) = -6.25 × 10^15 m/s^2. The acceleration is negative because the electron is slowing down.
The force on the electron due to the electric field is F = ma, where m is the mass of the electron (9.11 × 10^-31 kg). Substituting the values gives F = (9.11 × 10^-31 kg) * (-6.25 × 10^15 m/s^2) = -5.69 × 10^-15 N.
The strength of the electric field is E = F/q, where q is the charge of the electron (1.60 × 10^-19 C). Substituting the values gives E = (-5.69 × 10^-15 N) / (1.60 × 10^-19 C) = 3.56 × 10^4 N/C.
(b) The electron stops momentarily because it has lost all its kinetic energy due to the work done by the electric field. The electric field exerts a force on the electron in the opposite direction to its motion, causing it to decelerate. When the electron's kinetic energy has been completely converted into potential energy, it momentarily comes to a stop before being accelerated back in the opposite direction by the electric field.
Similar Questions
An Electron is accelerated to the right from rest across a potential difference of 9 volts then encounters a region of uniform electric field of strength 5.7 N/C directed to the right. (a) How far into the region with the electric field is the electron able to travel before it is brought to a halt? (7 marks) (b) What is the electric potential at the point the electron stops (relative to the point where the electron enters the field)? (3 marks)
The figure below shows an electron entering a uniform electric field perpendicularly betweenthe middle of two plates with a velocity of 5.0 × 107 m s−1. Two flat parallel plates, each oflength 12.0 cm, are separated by a distance of 1.5 cm.The potential difference between the plates is 210 V.(a) Calculate the magnitude of the electric field strength between the plates.(b) Determine the magnitude and direction of the acceleration of the electron.(c) Calculate the time for the electron to travel a horizontal distance equal to the length of theplates.(d) Use your answers in (c) to determine whether the electron will hit one of the plates oremerge from between the plates.
An electron moving at right angles to a 0.10-T magnetic field experiences an acceleration of 6.0x10'5 m/s. (a) What's its speed? (b) By how much does its speed change in 1 ns?
In the figure above, an electron is released at an angle of 45 degrees from the parallel-plate capacitor's positive side. The distance between the plates is 2.50 cm and the electric field strength inside the capacitor is 3.50×104 N/C. If the electron avoids touching the negative plate, what is its maximum possible initial speed?
An electron falls a distance of 4 cm in a uniform electric field of magnitude The time taken by electron in falling will be-
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.