Reflection of light using a mirror Refraction of light using various shaped optical mediums Total Internal Reflection (TIR) using a semi-circular perspex For Total Internal Reflection (TIR) to occur: 1) angle of incidence i is greater than the critical angle c 2) the light is travelling from an optically denser medium towards a less dense medium

If the circuit is open, i.e. there two ends of the solenoid is open, there is induced emf produced, but no induced current produced. That is why the magnet can fall through normal with free fall acceleration 10 m/s2. Only when the circuit is closed, there is an induced current flowing through. According to Lenz's law, the direction of the induced current is such that the magnetic effect opposses the change producing it, hence there is a repulsion force when the magnet is falling through the solenoid.