8.PS4.3

Digital waves carry information as a series of zeros and ones, known as binary code. Analog waves carry a continuous range of values. Since each piece of digital information is simply a one or zero, it is possible to perfectly reproduce digital information over and over again. So a copy of the information carried by a digital wave can be identical to the original wave. It is far more difficult to make a perfect copy of an analog wave because

• each individual piece of information is either a zero, a one, or a two.

• analog waves travel at speeds too great for modern technologies to use.

• most analog waves have wavelengths that are too long to reproduce in copies.

• the exact value of any one piece of information is not clearly defined.

Alison wants to record a song she wrote. The music studio records the music using digital technology instead of analog technology. Why does the music studio likely use digital technology for recording rather than analog technology?

• Digital technology produces more background noise in recordings than analog technology.

• Digital technology can store information more reliably than analog technology.

• Digital technology has been used longer than analog technology.

• Digital technology cannot be changed while analog technology can easily be modified.

Remote controls enable users to adjust the volume and channel of televisions without having to touch the television. Which of these best describes the signals sent by remote controls to televisions?

• electromagnetic waves

• gravitational energy

• potential energy

• sound waves

Digital information is converted and transmitted in certain numbers that create a pattern. Analog data is transmitted in continuous waves. Old records contain analog data but can be converted to digital recordings. Which of these statements best describes how digital data compares to analog data?

• Digital data takes more space to store than analog does.

• Digital data can be stored for a longer period of time than analog can.

• Digital data records more unwanted background noise than analog does.

• Digital data transmits signals more slowly than analog can.

Cell phone jammers work by interfering with the signals exchanged between cell phones and nearby cell phone towers. As a result, cell phones being affected by cell phone jammers do not receive communication signals from nearby towers. How do cell phone jammers disable the communication between cell phones and nearby cell phone towers?

• Cell phone jammers change the frequency of the signals emitted by cell phones and cell phone towers.

• Cell phone jammers reflect the signals emitted from cell phone towers away from cell phones in the area.

• Cell phone jammers absorb signals that are emitted by cell phone towers before they reach cell phones in the area.

• Cell phone jammers transmit powerful signals at the same frequency as the signals used by cell phones and cell phone towers.

Why is the weak analog signal harder to hear?

• The weak signal’s sound and clarity decrease corresponding to its amplitude.

• Radios have trouble distinguishing between weak signals and random noise.

• Increased distance causes wavelengths and frequencies to change.

• Radios have trouble connecting with lower-energy waves.

How can different types of programs all use the same binary code to function?

• One string of binary codes can simultaneously act as text, sound and image.

• Text binary uses 1s and 0s, while other programs use a different pair of numbers.

• Each program interprets the binary code differently, so the 1s and 0s can represent text, sound, or images.

• Music and images use longer strings of binary code than plain text.

The following is the graph of ___________________________

• An analog signal

• A digital signal

Which best compares the reliability of analog signals and digital signals?

• Only analog signals are reliable

• Analog signals are more reliable than digital signals

• Digital signals are more reliable than analog signals

• Both types of signals are equally reliable