પારરક્ત કિરણો કેવા છે A. અનુલંબ તરંગો B. લંબગત તરંગો C. યાંત્રિક તરંગો D. વિદ્યુતચુંબકીય તરંગો

Infrared rays are part of the electromagnetic spectrum, with wavelengths just longer than red light. Like all electromagnetic waves they are transverse (the electric and magnetic fields vibrate at right angles to the direction of travel) and need no medium. They are not longitudinal or mechanical waves, so the correct pair is B and D.