# electric filed a level physics

#1
http://www.theallpapers.com/papers/A...W-QP-JUN03.pdf
question three, i dont get why kinetic energy increase , is because as it moves away from a to b repulsive force
accelerates the electron, causing its kinetic energy to increase
Last edited by hkgbknhl; 2 years ago
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2 years ago
#2
When an electron moves from A to B, the electric field has to achieve (mechanical) work. Example: when its 1 V to move an electron, this work you need is 1 eV to come get through the field. When an electron changes from electrostatics to movement, kinetic energy increases. The higher the voltage of the electrical field the higher the work is needed that an electron moves through the field what influences the kinetic energy in turn: it increases again.

Just to test you: Look at the field's Voltage: in A the Voltage is -40 V, in B it is -10 V, the difference is 30 V. What do you think would it be, if B is in -20 V? is the kinetic energy higher or lower?

Spoiler:
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It is lower, because the difference (compared to -10 V) is 20 V! that is lesser than 30 V. Higher difference means a higher work has to achieve to get an electron from one certain point to another, thus more kinetic energy is required. Note: the higher the difference, the higher the kinetic energy!
Last edited by Kallisto; 2 years ago
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