This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anesthesia Machine, Subject name: Anaesthesia
Physical law made use in flow meter is:- 
Select and explain. 
A. Henrys law, B. Grahams law, C. Daltons law, D. Faraday'slaw
D: Faraday'slaw
Answer: D: Faraday'slaw 
Explanation: Velocity Flow Meters. Magnetic flow meters operate on Faraday'slaw of electromagnetic induction that states that a voltage is induced when a conductor moves through a magnetic field. The liquid serves as the conductor and the magnetic field is created by energized coils outside the flowtube.