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Questions and Answers
What is the primary role of electric signals in communication?
What is the primary role of electric signals in communication?
Which type of signal is defined as continuous and varies smoothly over time?
Which type of signal is defined as continuous and varies smoothly over time?
In the context of mobile communication, what does the smartphone do with the analog signal it receives?
In the context of mobile communication, what does the smartphone do with the analog signal it receives?
What is the process called that converts continuous analog signals into discrete digital signals?
What is the process called that converts continuous analog signals into discrete digital signals?
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Which characteristic best describes digital signals?
Which characteristic best describes digital signals?
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What happens after an electromagnetic wave is transmitted to a smartphone?
What happens after an electromagnetic wave is transmitted to a smartphone?
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Which of the following is NOT a characteristic of analog signals?
Which of the following is NOT a characteristic of analog signals?
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Which of the following systems requires signals to be represented in binary form for processing?
Which of the following systems requires signals to be represented in binary form for processing?
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What is a major characteristic of Alternating Current (AC) compared to Direct Current (DC)?
What is a major characteristic of Alternating Current (AC) compared to Direct Current (DC)?
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How does the flow of electrons in Direct Current (DC) differ from Alternating Current (AC)?
How does the flow of electrons in Direct Current (DC) differ from Alternating Current (AC)?
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What is the frequency of Alternating Current (AC) typically in many countries?
What is the frequency of Alternating Current (AC) typically in many countries?
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What effect does the rotating magnetism in Alternating Current have on current flow?
What effect does the rotating magnetism in Alternating Current have on current flow?
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What form does an electric signal take when transmitting information?
What form does an electric signal take when transmitting information?
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What happens to a photo transmitted over a mobile network before reaching the receiving device?
What happens to a photo transmitted over a mobile network before reaching the receiving device?
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Which statement is correct about the direction of current flow in AC and DC?
Which statement is correct about the direction of current flow in AC and DC?
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Which statement about energy loss in DC compared to AC is true?
Which statement about energy loss in DC compared to AC is true?
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What is the main characteristic of Direct Current (DC)?
What is the main characteristic of Direct Current (DC)?
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Which of the following statements accurately describes Alternating Current (AC)?
Which of the following statements accurately describes Alternating Current (AC)?
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Which unit is used to measure electric current?
Which unit is used to measure electric current?
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In which scenario would you most likely encounter Direct Current (DC)?
In which scenario would you most likely encounter Direct Current (DC)?
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What happens to the movement of electrons in a conductor when a voltage is applied?
What happens to the movement of electrons in a conductor when a voltage is applied?
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Which of the following best distinguishes between Direct Current (DC) and Alternating Current (AC)?
Which of the following best distinguishes between Direct Current (DC) and Alternating Current (AC)?
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What does the term 'electric current' refer to?
What does the term 'electric current' refer to?
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Which example corresponds to Alternating Current (AC)?
Which example corresponds to Alternating Current (AC)?
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What is the purpose of the sampling process in signal processing?
What is the purpose of the sampling process in signal processing?
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According to the Nyquist-Shannon Sampling Theorem, what sampling rate is necessary for accurate digital conversion?
According to the Nyquist-Shannon Sampling Theorem, what sampling rate is necessary for accurate digital conversion?
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If an analog signal has a maximum frequency of 5 kHz, what is the minimum sampling rate required?
If an analog signal has a maximum frequency of 5 kHz, what is the minimum sampling rate required?
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What does the term 'quantization' refer to in signal processing?
What does the term 'quantization' refer to in signal processing?
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How is the number of quantization levels determined?
How is the number of quantization levels determined?
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What is the final result of the coding process in signal processing?
What is the final result of the coding process in signal processing?
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What is the relationship between sampling frequency and sampling interval?
What is the relationship between sampling frequency and sampling interval?
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If 2 bits of quantization are used, how many quantization levels will be available?
If 2 bits of quantization are used, how many quantization levels will be available?
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Study Notes
Course Objective
- Define electric current and alternating current
- Understand the difference between direct and alternating current
- Introduce electrical signals
- Explain how to convert analog signals to digital signals
Electric Current
- Electric current is the movement of electrons from one atom to another in the same direction
- This flow is measured in amperes (A)
- In a conductor like copper, there are free electrons moving between atoms
- Applying voltage creates a flow of electrons from the negative terminal to the positive terminal through a conductor (like a copper wire)
- This electron flow is called electric current
Current Types
- Direct Current (DC): Electrons flow continuously in one direction (e.g., 12V car battery, 5V USB)
- Alternating Current (AC): Electrons periodically reverse direction (e.g., 230V household electricity)
AC vs. DC
| Feature | Alternating Current (AC) | Direct Current (DC) |
|---|---|---|
| Transfer | Easily transferred over long distances with minimal energy loss | Cannot be transferred over long distances; loses power |
| Direction | Direction of electron flow changes periodically | Steady flow in one direction |
| Frequency | Frequency varies by country, commonly 50Hz or 60Hz | No frequency (zero frequency) |
| Electron Movement | Electrons move back and forth | Electrons move in one direction continuously |
Electric Signal
- An electric signal carries information in the form of varying voltage or current
- Used in communication devices, computers, and other systems
- Examples include transmission of photos via mobile networks
Signal Types
- Analog Signals: Continuous and smooth; their value can be anything within a range (e.g., sound waves, temperature readings)
- Digital Signals: Discrete and non-continuous; consist of binary values (0s and 1s) (e.g., computer signals, digital watches)
Analog-to-Digital Conversion (ADC)
- Converts continuous analog signals into discrete digital signals
- Sampling: Measuring analog signal at regular intervals (sampling points)
- Sampling Rate: The frequency (measured in Hertz (Hz)) at which the signal is sampled, which is twice the highest frequency (2F) in the input analog signal.
- Quantization: Mapping continuous amplitude values to discrete levels (quantization levels) based on the number of bits used for the conversion process (e.g. 2 bits = 4 levels)
- Example: Converting human voice (up to 3 kHz) requires a sampling rate of at least 6 kHz.
- For a certain signal (e.g., 2.5ms signal), with 6000 samples/sec = 15 values are extracted from the signal, determining the sampling frequency and interval.
Coding Digital Signals
- Binary codes (0s and 1s) are used to represent the quantized signal values
- Converting sampled, quantized values to digital form.
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Description
Test your understanding of electric current, including the differences between direct current (DC) and alternating current (AC). This quiz will also cover the basics of electrical signals and the conversion from analog to digital signals. Dive into the world of electricity and enhance your technical knowledge.
