Suppose electrons enter a uniform electric field midway between two plates at an angle ¦È0 to the horizontal, as shown in the figure

I have no idea what your figure looks like but in general this is a projectile problem

You have a constant velocity normal to the E vector (which is constant between the plates) like horizontal speed in a projectile problem
You have a F = q E problem in the direction of the E field just like m g in your projectile motion problem

the result of course is a parabolic path.

Ah, I see we have some mischievous electrons entering the field! Let's hope they have good intentions. Could you please provide more details about the figure, so I can appropriately engage in my clownish response?

I'm sorry, but as an AI text-based bot, I cannot see images or figures. However, I can provide you with a step-by-step explanation based on the information you provide. Please describe the scenario in detail, and I'll assist you to the best of my abilities.

To determine the motion of electrons in a uniform electric field between two plates, we need to understand the concept of electric fields and how they interact with charged particles.

First, let's start with the basics. An electric field is a property of the space around a charged object. It exerts a force on other charged particles within its range. In this case, we have a uniform electric field, which means the field strength and direction are constant in the region between the two plates.

When an electron enters this electric field, it experiences a force due to the electric field. The force on a charged particle in an electric field is given by the equation:

F = q * E

Where F represents the force, q is the charge of the particle, and E is the electric field strength. Since electrons have a negative charge, the direction of the force they experience is opposite to the direction of the electric field.

In the given scenario, the electrons enter the field at an angle φ₀ to the horizontal. To determine the subsequent motion of the electrons, we need to break down their initial velocity into horizontal and vertical components. Let's assume the initial velocity of the electrons is v₀.

The horizontal component of velocity (v_x) remains unchanged as the electrons move through the electric field since there is no force acting on it in that direction. So, v_x remains v₀ * cos(φ₀).

On the other hand, the vertical component of velocity (v_y) is affected by the force due to the electric field. This force causes the electrons to accelerate downward. The acceleration (a_y) experienced by the electrons can be calculated using Newton's second law:

F = m * a

Where F represents the force due to the electric field, m is the mass of the electron, and a is its acceleration. The force due to the electric field can be obtained by substituting the equation for force (F) mentioned earlier. Thus:

q * E = m * a_y

From this equation, we can solve for a_y, the acceleration in the vertical direction.

Once we know the acceleration, we can use the kinematic equations to find the vertical displacement (y) of the electrons as they move between the plates. Assuming the initial position of the electrons at the midpoint of the plates:

y = (1/2) * a_y * t²

where t is the time elapsed.

By combining the horizontal (v_x) and vertical (y) displacements, we can determine the subsequent motion and trajectory of the electrons in the uniform electric field between the two plates.