If the velocity of electromagnetic wave in free space is 3 × 10⁸ m/s, then the velocity in a medium with εr of 4.5 and μr of 2 would be

• A. 27 × 10⁸ m/s
• B. 9 × 10⁸ m/s
• C. 1 × 10⁸ m/s
• D. 3 × 10⁸ m/s

Answer: (C)

Speed of EM wave in medium = C/√(εr*μr)
= (300000000)/√9
= 300000000/3
= 100000000
= 1*10⁸ m/s