# Some more help pls

1. Jul 15, 2005

### hotstuff

(c=keA/d
(b) Estimate the charge generated at each end of a catfish as follows: Treat the catfish as a parallel plate capacitor with plates of area 1.8 * 10-2 m2, separation 1. m, and filled with dielectric with a dielectric constant k = 95. with v=350. ans should be in C

seems easy enough but no getting the same ans at the back of the stupid book. this is what i have done so far.
find capacitance of parallel plate capacitor= c=keA/d = 8.85*10^-12*95*1.8*10m^2/1 = ans

and then use the q=cv= above ans*350 the back of the book is 5.3*10-9, i am getting 5.0 *10^-13 what is really good. any help appreciated

2. Jul 16, 2005

### geosonel

your approach is correct. book is also correct. check for careless errors.

$$Capacitance \ = \ \frac{(95)(8.85 \, \times \, 10^{-12})(1.8 \, \times \, 10^{-2})}{1.0} \ = \ 1.51 \, \times \, 10^{-11} \, Farads$$

$$Charge \ = \ Capacitance \, \times \, Voltage \ = \ (1.51 \, \times \, 10^{-11}) \, \times \, (350) \ = \ 5.29 \, \times \, 10^{-9} \, Coulombs$$