Question

The speed of light in a medium of refractive index 3 is (1)3x10^8 m/s
(2)2x10^8 m/s
(3)1x10^8 m/s
(4)0.5x10^8 m/s​

Answer 1

Speed of light in vacuum = 3 x 108 m/s Refractive index of the medium = Speed of light in vacuum/Speed of light in medium =1.5=3x108/v => v= 3 x 108/1.5 =2 x 108 m/s Hence, the speed of light in the medium of refractive index 1.5 is 2 x 108 m/s

Answer 2

$\huge\fbox\colorbox{red}{✞Aɴsᴡᴇʀ}$

sᴘᴇᴇᴅ ᴏғ ʟɪɢʜᴛ ᴏғ ᴠᴀᴄᴄᴜᴍ = 3 × 108 ᴍ/s

$\pmb{{\underline{\bigstar{ʀᴇғʀᴀᴄᴛɪᴠᴇ \: \: ɪɴᴅᴇx \: \: ᴏғ \: \: ᴍᴇᴅɪᴜᴍ \: = sᴘᴇᴇᴅ \: ᴏғ \: ʟɪɢʜᴛ ɪɴ \: ᴠᴀᴄᴄᴜᴍ \: / \: sᴘᴇᴇᴅ \: ᴏғ \: ʟɪɢʜᴛ \: ɪɴ \: ᴍᴇᴅɪᴜᴍ }}}}$

⇨ 1.5 = 2 × 108/ ᴠᴀᴄᴄᴜᴍ

⇨ᴠᴀᴄᴄᴜᴍ = 2 × 108/1.5

⇨ 2 × 108 ᴍ/s

ʜᴇɴᴄᴇ, ᴛʜᴇ sᴘᴇᴇᴅ ᴏғ ʟɪɢʜᴛ ɪɴ ᴛʜᴇ ᴍᴇᴅɪᴜᴍ ᴏғ ʀᴇғʀᴀᴄᴛɪᴠᴇ ɪɴᴅᴇx 1.5 ɪs 2× 108 ᴍ/s