The more pixels a digital image consists of, the clearer the image. A) True B) False
A
What do all signals that are used to communicate have in common? A) Light waves B) Send information C) Printed words D) Sounds
B) Send information
Before a signal is sent, it must be decoded.A) True B) False
B
An analog signal is one that changes continuously. A) True B) False
A
Radio waves are an example of a digital signal. A) True B) False
B
How does noise affect a signal? A) Deteriorates B) Amplifies C) Helps travel D) Changes media
A) Deteriorates
Digital signals are more affected by noise than analog signals. A) True B) False
B
All of the following are EM waves used to transmit signals except: A) Sound waves B) Light C) Radio D) Microwaves
A) Sound waves
Computers use a series of ___ numbers to encode information. A) decimal B) binary C) random D) analog
B) binary
Identify three devices that were developed to send or receive signals carried by electromagnetic waves.
Sample Answers: Cell phone, radio, garage door opener
Which correctly orders the steps of communication using signals? A) Encode, transmit, decode B) Transmit, encode, decode C) Decode, transmit, encode D) Transmit, decode, encode
A) Encode, transmit, decode
For which type of signals does noise alter the original information? A) Analog only B) Digital only C) Both D) Neither
A) Analog only
Which best describes binary numbers? A) Continuously changing wave B) Two discrete values C) Large array of values D) Set of 4–5 numbers
B) Two discrete values
Electronic signals can travel very long distances in ___ fibers, due to total internal reflection.B) optical C) magnetic D) glass
B) optical
Which is the best model of an analog signal? A) a smooth wave B) a light switch C) a series of 1s & 0s D) pulses
A) a smooth wave
Which best compares reliability of analog and digital signals? A) Only analog is reliable B) Analog is more reliable C) Digital is more reliable D) Same reliability
C) Digital is more reliable
Sign language and written language are examples of signals used to communicate.A) True B) False
A
Figure 1: Analog – continuous voltage changes; Figure 2: Digital – only “on/off” values
Describe pixels and explain how digital cameras use pixels to form images.
Pixels hold color values. More pixels mean sharper images. Cameras convert light to digital data per pixel.
Describe three characteristics of electromagnetic waves that make them useful for transmitting signals.
Travel fast, no medium required, easily modulated
Evelyn plays a voice recording 100 times using both tape and a computer. a. What difference will she notice? b. Why is there a difference?
a) Tape recording becomes distorted; computer recording stays clear. b) Analog tape wears out; digital data doesn’t degrade with playback.
What is a disadvantage of using radio waves to transmit information? A) Don’t move matter B) Travel far C) Carry info D) Lose energy
D) Lose energy