An electron is released from rest in a uniform electric field and accelerates to the north at a rate of 115 m/s squared. What are the magnitude and direction of the electric field?

Question

anonymous · Answer

Force=mass*acceleration
But the force on the electron is because of the electric field.
Since electron is negatively charged. If Electric field is in east direction, the force on electron will be in west direction. So electron accelerates in west.
Applying same thing,
Direction of electric field should be in South direction as electron is accelerating towards North direction.

Magnitude:
Force on charge q in a electric field E should be
F=qE ; q is the charge of electron E is magnitude of Electric field
but F=ma ; m is mass of electron. a is the acceleration
ma=qE
E=ma/q.

Substitute mass of electron, acceleration, charge of electron (simply put the value no negative needed as we already took care it in direction. We are calculating only magnitude)