If $q_{f}$ is the free charge on the capacitor plates and $q_{b}$ is the bound charge on the dielectric slab of dielectric constant $k$ placed between the capacitor plates,then the bound charge $q_{b}$ can be expressed as:

• A
  $q_{b} = q_{f} \left(1 - \frac{1}{k}\right)$
• B
  $q_{b} = q_{f} \left(1 - \frac{1}{\sqrt{k}}\right)$
• C
  $q_{b} = q_{f} \left(1 + \frac{1}{\sqrt{k}}\right)$
• D
  $q_{b} = q_{f} \left(1 + \frac{1}{k}\right)$