A solid plastic cylinder is placed in a liquid with refractive index $1.4$. Light travelling in the plastic cylinder hits the inside surface at an angle of incidence of $70^\circ$. The light undergoes total internal reflection. Find the value of the critical angle in the plastic and the refractive index of the plastic.
- Acritical angle greater than $70^\circ$; refractive index greater than $1.4$
- Bcritical angle greater than $70^\circ$; refractive index less than $1.4$
- Ccritical angle less than $70^\circ$; refractive index greater than $1.4$
- Dcritical angle less than $70^\circ$; refractive index less than $1.4$