An electron is launched from rest at point toward point

PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential

Problem

An electron is launched from rest at point

A

toward point

B

, which lies

5.0\,\text{cm}

away along the axis of a uniform electric field. Point

B

is at an electric potential

\Delta V=+200\,\text{V}

relative to point

A

. Assume the only force on the electron is the electrostatic force. Use

e=1.60\times10^{-19}\,\text{C}

and

m_e=9.11\times10^{-31}\,\text{kg}

. (a) Calculate the speed of the electron as it reaches point

B

. (b) The initial launch speed is now changed to

3.0\times10^{6}\,\text{m}\!\cdot\!\text{s}^{-1}

while the potential difference remains

+200\,\text{V}

. Determine the potential difference (magnitude and sign) that would be required, instead of

+200\,\text{V}

, to bring an electron with that initial speed to rest exactly at point

B