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Titan97
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Homework Statement
Show the the induced charge density on a dielectric placed inside a capacitor is given by $$\frac{k-1}{k}\sigma$$ where ##\sigma## is the charge density of the capacitor plates and ##k## is the dielectric constant.
Homework Equations
$$E=\frac{E_0}{k}$$
The Attempt at a Solution
Using the above image, let ##E_0## be the electric field before inserting the dielectric and ##E_i## be the induced electric field.
Total electric field between the plates $$E=E_0-E_i$$
$$\frac{E_0}{k}=E_0-E_i$$
$$E_i=\frac{k-1}{k}E_0$$
Now, ##E_0## is the total electric field due to the plates of the capacitor which is equal to ##\frac{\sigma}{k\epsilon_0}##. The factor of ##k## is because the medium is not vacuum anymore. (Clarification needed because in my book, K does not come in both the expressions for ##E_0## and ##E_i##).
Similarly, ##E_i=\frac{\sigma'}{k\epsilon_0}##
Hence, ##\sigma'=\frac{K-1}{K}\sigma##.
Although I got the answer, in my book, its given ##E_0=\frac{\sigma}{\epsilon_0}## and ##E_I=\frac{\sigma'}{k}##. The K term is missing. Is it a printing error or am I wrong?