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Learning Introductory Physics with Activities

Section 24.4 Using Electric Potential

Subsubsection Activities

Activity 24.4.1. The Old TV.

Old TVs worked by sending electrons from the back of the TV to the front of the TV. The electric potential difference between the front and the back of the TV was ΔV = 25,000 V.

(a)

Make a side-view sketch of the inside of the TV. Label each end with the corresponding value of the electric potential.

(b)

Determine the change in electric potential energy (\(\Delta U_E\)) for a single electron.

(c)

Determine the speed of an electron when it reaches the screen.

Activity 24.4.2. Charge Launcher III.

Recall the device described in Charge Launcher I.

(a)

Find the electric potential difference \(\Delta V\) between the middle of the tube and the top of the tube.

(b)

Sketch a graph of the electric potential \(\Delta V\) vs. height \(y\) in the tube.

(c)

Use the additional information from Charge Launcher II.
For each of the following types of energies, determine if they are positive, negative, or zero as the heavy ball moves upward in the launcher: \(\Delta K\text{,}\) \(\Delta U_g\text{,}\) and \(\Delta U_E\text{.}\)

(d)

How fast is the ball moving at the top of the tube?