1)The reason as to why scientists opt to transmit data at lower frequency instead of electromagnetic even if it can carry more data at a higher frequencies is because using higher frequencies of electromagnetic spectrum travel shorter distances but have higher data carrying capacity.So this physical characteristic of electromagnetic waves limits the range and availability of frequencies for sending information.
2) Limitations of using electromagnetic waves in sending communication
communication is a process of transmitting and receiving information in the form of signals.high technology communication use electromagnetic waves,there are various types of electromagnetic waves which are used in communication which include radio-waves,microwaves,infrared e.t.c some of their limitations are
i)Because there is limited number of broadcast frequencies the use of transmitters must be restricted in some way or they will seriously interfere with each other.
ii)Through the air signals can be distorted by atmospheric conditions and signals from space are sometimes distorted by solar activity
iii)physical activities such as mountains and buildings can prevent or interfere with some transmissions
iv)Through the air signals are not private,so any tuned receiver within the range can pick up them.
3)Differences between digital and analogue signals
Analogue and digital signal are used to transmit information usually through electric signals.
An analogue signal is continuous wave denoted by sine wave and may varry in signal strength (amplitude) or frequency(time) an example is sound from human voice is analogue because waves are continuous..
A digital signal is a signal in which the original information is converted into a string of bits before being transmitted .example a must for computer processing where is described as using (0s and 1s)and therefore can not take any fractional value.
4)Advantages of using digital signals over analogue signals
one advantage of digital signals are inherently less susceptible than analog signals to interference caused by noise because with digital signal it is not necessary to evaluate precise amplitude,frequency or phase.
Another advantage based in capacity is that digital signals carry more information per second than analogue signals.
Digital signals maintain their quality over long distances better than analogue signals.
5)How we use digital and analogue signals in our everyday live
digital signal processing is the way of life of current generation
example is mobile phones do alot of digital signal processing .they process our our speech digitally to remove background noise,echo e.t.c
Television also do a lot of digital processing of video,audio signal to present them in a better way.
How radio telescopes are used to explore space
A radio telescope is a specialized antenna and radio receiver used to receive radio waves from astronomical radio sources in the sky in radio astronomy.It has several main parts, a dish and antenna,a receiver,a detector and an analyzer.The dish collects the radio signals from space ad focuses them on the antenna.
6)How radio waves are used on earth
Radio waves are used to transmit television and radio programs They have longer wave lengths and are reflected by the ionosphere
7) Reasons why telescopes convert radio waves (analog) to electrical(digital) signals for analysis
This is because signals can be easily stored and transmitted in digital form.The analog is continuous in time and it is necessary to convert this to a flow of digital values.
Answer:
1. the set of real numbers between 0.1 and 0.2
2. the set of all negative integers greater than negative 1 trillion
3. the set of all java and C programs
Explanation:
A set is countable if it is either finite or has the same cardinality as the set of positive integers. The inverse of this set type is uncountable.
The set of real numbers between 0.1 and 0.2, all negative integers greater than negative 1 billion, and a set of java and C programs are all countable sets, so are considered countably infinite.
Answer:it has high coupling
Explanation: Coupling is the property in the field of computer program that is defined as the functions ,data and codes of the program are dependent on each other and cannot be changed independently if requires. Thus,high amount of coupling is not considered as good factor due to high interdependence. Loose coupling can be still permitted.
Other options are correct because name of the class should reflect the purpose and well defined responsibilities should be present, modeling of certain component and high cohesion means keeping similar functions togather is also required. So, the only bad factor is high coupling
