COMMUNICATION SYSTEMS

✘ ✘ ✘ None of these ✔ NULL ✔ NULL NULL

2400 ✘ 2200 ✘ 2000 ✘ 1800 ✔ NULL ✔ NULL NULL

✘ ✘ ✘ ✔ NULL ✔ NULL NULL

Microwave region ✘ Ultraviolet or visible region ✘ Infrared region ✘ None of the above ✔ NULL ✔ NULL NULL

Omnidirectional type ✘ Vertical type ✘ Horizontal type ✘ None of these ✔ NULL ✔ NULL NULL

Interference of waves ✘ Diffraction of waves ✘ Polarisation of waves ✘ None of these ✔ NULL ✔ NULL NULL

Ground wave propagation is for high frequency transmission ✘ Sky wave propagation is facilitated by ionospheric layers ✘ Space wave is of high frequency and is suitable for line of sight communication ✘ Space wave is used for satellite communication ✔ NULL ✔ NULL NULL

Microwaves ✘ Surface waves ✘ Sky waves ✘ Space waves ✔ NULL ✔ NULL NULL

Dwarfs ✘ Sixth magnitude stars ✘ Second magnitude ✘ Zero magnitude stars ✔ NULL ✔ NULL NULL

Optical fibres can be of graded refractive index ✘ Optical fibres are subjected to electro-magnetic interference from outside ✘ Optical fibres have extremely low transmission loss ✘ Optical fibres may have homogeneous core with a suitable cladding ✔ NULL ✔ NULL NULL