# A parallel plate condenser has a capacitance 50μF in air and 110μF when immersed in an oil. The dielectric constant ′k′ of the oil is ?A)  0.45B)  0.55C)  1.10                                  D)  2.20

$C_{1}=50\mu F=\frac{\varepsilon _{0}A}{d}$(in air)
$C_{2}=110\mu F=\frac{\varepsilon _{0}kA}{d}$(When immersed in oil)
$\frac{C_{2} }{C_{1}}=k=2.20$