Electric Potential Energy Video Lessons

Video Thumbnail

Concept

Problem: A 2.5 mm -diameter sphere is charged to -4.6 nC . An electron fired directly at the sphere from far away comes to within 0.35 mm of the surface of the target before being reflected.What was the electron's initial speed?At what distance from the surface of the sphere is the electron's speed half of its initial value?What is the acceleration of the electron at its turning point?

FREE Expert Solution

Kinetic energy,

K.E=12mev2

Potential Energy,

U=kq1q2r

Force,

F = ma

r = d /2 = 2.5 mm/ 2 ( 1 m/ 1000 mm) = 1.25 × 10-3 m

qs = - 4.6 nC = - 4.6 × 10-9  C

qs = - 1.6 nC = - 1.6 × 10-9  C

me = 9.1 × 10-31 kg

d = 0.35 mm = 0.35 × 10-3 m

a)

From the law of conservation of energy;

12mev2=kqsqe(r+d)v=2kqsqeme(r+d)=2(9×109)(-4.6×10-9)(-1.6×10-19)(9.1×10-31)(1.25×10-3+0.35×10-3)

v = 9.54  × 107 m/s

View Complete Written Solution
Problem Details

A 2.5 mm -diameter sphere is charged to -4.6 nC . An electron fired directly at the sphere from far away comes to within 0.35 mm of the surface of the target before being reflected.

What was the electron's initial speed?

At what distance from the surface of the sphere is the electron's speed half of its initial value?

What is the acceleration of the electron at its turning point?

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Electric Potential Energy concept. You can view video lessons to learn Electric Potential Energy. Or if you need more Electric Potential Energy practice, you can also practice Electric Potential Energy practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Krishna & Weatherford's class at UF.