(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The electrostatic potential energy of a system of point charges q1 = 1 µC, q2 = 2 µC, and q3 = 3 µC at the corners of an equilateral triangle whose side s = 30 cm is

a. 1.10 J

b. 0.990 J

c. 0.631 J

d. 0.330 J

e. 0.123 J

2. Relevant equations

See below.

3. The attempt at a solution

PE = k*q*q_0/(r)

PE_total = [(k*(1*10^-6 C)*(3*10^-6 C)/(.30 m)] + [(k*(1*10^-6 C)*(2*10^-6 C)/(.30 m)] + [(k*(3*10^-6 C)*(2*10^-6 C)/(.30 m)]

= k/.30 m*[(3*10^-12 C^2) + (2*10^-12) + (6*10^-12)] = 0.3296 J ??

1. The problem statement, all variables and given/known data

Two flat parallel plates are a distance d = 0.40 cm apart. The potential difference between the plates is 360 V. The electric field at a point midway between the plates is approximately

a. 90 kN/C

b. 3.6 kN/C

c. 0.9 kN/C

d. zero

e. 3.6*10^5 N/C

2. Relevant equations

See below.

3. The attempt at a solution

E = delta V/d = 360 V/0.004 m = 90,000 V/m = 90,000 N/C ?

Thanks.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Parallel Plates and Electric Field

**Physics Forums | Science Articles, Homework Help, Discussion**