What is the change in the observed frequency called?

Doppler shift

Delta shift

Delta frequency

Differential frequency

Correct Answer : Doppler shift

Explanation : In Doppler radar, there is a change in reflected frequency when there is relative motion between the transmitter and the receiver. This change in frequency is called the Doppler shift and is proportional to the relative speed between the transmitter and receiver.

Recently Updated in Avionics Questions

Anti reflection coated optics reduce ________

Refraction

Reflection angle

Intensity of star image

Optical transmission losses

Correct Answer : Option (D) : Optical transmission losses

Explanation : For anti-reflection coated optics, the optical transmission losses may be 1% or 2% at each air to glass or glass to air optical control surface within the telescope, including windows or sensor covers or surfaces. For uncoated optics, the loss per surface is about 4% to 5%.

The ratio of the focal length to aperture is called the ________

Focal number

f/ number

Critical aperture

Effective aperture

Correct Answer : Option (B) : f/ number

Explanation : The ratio of focal length to aperture is called the f/ number. For example, an f/10 telescope may have a 30 in. focal length and a 3 in. aperture.

The physical size of the star depends upon _____

Shape of image

Colour of image

Angular size of image

Intensity of image

Correct Answer : Option (C) : Angular size of image