Which of the following are true about the infra-red radiation?
i. it is invisible
ii. it is called heat ray
iii. its frequency is higher than that of blue light
iv. it travels as a transverse wave
i, ii, iii and iv
i, ii, iv only
i, iii, iv only
ii, iii, iv only
Correct answer is B
No explanation has been provided for this answer.