What was the preferred material for varying resistance in telephone transmitters?
- Aluminum
- Copper
- Carbon
- Iron
Correct Answer: Carbon
Correct Answer Explanation: Carbon’s ability to change resistance under pressure made it ideal for transmitting sound through early telephones. It was favored over other materials like aluminum, copper, and iron.
What invention allowed for the transmission of voice currents over longer distances?
- The induction coil
- The magneto-bell
- The Shreeve repeater
- The multiple switchboard
Correct Answer: The Shreeve repeater
Correct Answer Explanation: The Shreeve repeater, invented in the late 19th century, used a telephone receiver and a carbon transmitter to amplify the signal, making it possible to transmit voice currents over greater distances.
What was the primary challenge in creating early automatic telephone systems?
- The difficulty in replacing manual switching with a reliable automated system.
- The cost of developing and installing the equipment.
- The lack of skilled engineers to design and maintain the systems.
- The resistance of the public to adopting new technology.
Correct Answer: The difficulty in replacing manual switching with a reliable automated system.
Correct Answer Explanation: While cost, skilled labor, and public acceptance played roles, the biggest hurdle in early automatic telephone systems was creating a reliable system that could effectively replace the existing manual switchboards.
What did the first automatic switching equipment attempt to do?
- Directly connect each line in the central office to every other line.
- Use a series of relays to route calls through the system.
- Employ a central computer to manage call routing.
- Utilize a combination of manual and automated switching.
Correct Answer: Directly connect each line in the central office to every other line.
Correct Answer Explanation: The first attempts at automatic switching were overly ambitious, trying to connect every single line in the central office to every other line. This proved to be impractical and unreliable, leading to the development of more efficient methods like trunking.
What was the major advancement that allowed each operator on a multiple switchboard to reach every line in the exchange?
- The invention of the induction coil
- The introduction of the carbon transmitter
- The use of a common battery system
- The invention of the multiple switchboard
Correct Answer: The invention of the multiple switchboard
Correct Answer Explanation: The multiple switchboard, a breakthrough in manual telephone systems, enabled each operator to access all lines in the exchange, dramatically improving service and efficiency.
What was the primary reason copper wires quickly replaced iron wires in telephone lines?
- Copper was cheaper and easier to obtain.
- Copper was lighter and more flexible.
- Copper offered superior conductivity and resistance to rust.
- Copper was more resistant to electrical interference.
Correct Answer: Copper offered superior conductivity and resistance to rust.
Correct Answer Explanation: Copper’s superior conductivity and resistance to rust made it a better choice for telephone lines than iron, which was prone to corrosion and less efficient in transmitting electrical signals.
What did Oliver Heaviside propose to improve long-distance transmission?
- Increasing the inductance of telephone lines
- Reducing the capacity of telephone lines
- Using a more powerful battery for the transmitter
- Adding a repeater to the line at specific intervals
Correct Answer: Increasing the inductance of telephone lines
Correct Answer Explanation: Oliver Heaviside, a pioneering physicist, proposed that increasing the inductance of telephone lines would counteract the harmful effects of capacity, thereby improving long-distance transmission.
What was the primary purpose of Pupin loading coils?
- To reduce the voltage loss in long telephone lines
- To increase the speed of signal transmission
- To counter the effects of capacity and reduce signal attenuation and distortion.
- To improve the clarity of the sound transmitted over long distances.
Correct Answer: To counter the effects of capacity and reduce signal attenuation and distortion.
Correct Answer Explanation: Pupin loading coils, inserted at specific points along telephone lines, were designed to increase inductance and counteract the negative effects of capacity, reducing signal attenuation and distortion, and improving long-distance transmission.
Which of the following is NOT a type of battery used in early telephone and telegraph systems?
- Gravity cell
- Fuller cell
- Chloride of silver cell
- Edison cell
Correct Answer: Edison cell
Correct Answer Explanation: The Edison cell, a type of storage battery using nickel and iron electrodes, was developed later in the 20th century and was not in use during the early days of telephony and telegraphy. The other options, the Gravity cell, Fuller cell, and Chloride of silver cell, were all common batteries used in these early systems.
What is the approximate speed of sound in air?
- 500 feet per second
- 750 feet per second
- 1,090 feet per second
- 1,500 feet per second
Correct Answer: 1,090 feet per second
Correct Answer Explanation: The speed of sound in air is approximately 1,090 feet per second. This value is essential for understanding how sound waves travel and how they are transmitted in telephone systems.
What is the typical range of fundamental frequencies for the human male speaking voice?
- 32 to 120 vibrations per second
- 85 to 160 vibrations per second
- 150 to 320 vibrations per second
- 250 to 500 vibrations per second
Correct Answer: 85 to 160 vibrations per second
Correct Answer Explanation: The typical range of fundamental frequencies for the human male speaking voice is between 85 and 160 vibrations per second. This range plays a crucial role in understanding how the human voice is transmitted and received in telephone systems.
What is the approximate weight of a copper wire with a diameter of .08 inch per mile?
- 50 pounds
- 75 pounds
- 100 pounds
- 125 pounds
Correct Answer: 100 pounds
Correct Answer Explanation: A copper wire with a diameter of .08 inch weighs approximately 100 pounds per mile. This information is useful for understanding the weight and size considerations involved in building telephone lines.
Which of the following types of insulators provide the greatest capacitance?
- Dry paper
- Rubber
- Gutta-percha
- All of the above
Correct Answer: All of the above
Correct Answer Explanation: Rubber and gutta-percha insulators can have capacities up to twice that of dry paper, while dry paper itself has a non-negligible capacity. This knowledge is important for understanding the electrical properties of telephone lines and how insulators affect signal transmission.
What is the approximate voltage of a gravity cell?
- 0.5 volts
- 1.08 volts
- 1.5 volts
- 2.0 volts
Correct Answer: 1.08 volts
Correct Answer Explanation: A gravity cell, a type of battery used in early telephone systems, has a voltage of approximately 1.08 volts. This is important for understanding the power sources used to drive early telephone equipment.
What is the typical output current of a good 2-3/4 inch by 6 inch dry cell on a short circuit?
- 5 to 10 amperes
- 10 to 15 amperes
- 18 to 20 amperes
- 25 to 30 amperes
Correct Answer: 18 to 20 amperes
Correct Answer Explanation: A good 2-3/4 inch by 6 inch dry cell, a common battery in early telephone systems, can provide a short-circuit current of 18 to 20 amperes. This knowledge helps understand the power capacity of these batteries.
What is the approximate electromotive force of a LeClanché cell?
- 0.8 volts
- 1.03 volts
- 1.47 volts
- 1.8 volts
Correct Answer: 1.47 volts
Correct Answer Explanation: The LeClanché cell, another type of battery used in early telephone systems, has an electromotive force of approximately 1.47 volts. This value is essential for understanding the power sources used to operate early telephone equipment.
What is the typical current of a magneto generator?
- 100 cycles per minute
- 500 cycles per minute
- 1,000 cycles per minute
- 2,000 cycles per minute
Correct Answer: 1,000 cycles per minute
Correct Answer Explanation: A magneto generator, a device used in early telephone systems to generate alternating current, typically produces a current of about 1,000 cycles per minute. This knowledge is important for understanding the operation of early telephone signaling systems.
What type of signal was the earliest electric signal?
- The telephone receiver signal
- The telegraph sounder signal
- The magneto-bell signal
- The wireless signal
Correct Answer: The telegraph sounder signal
Correct Answer Explanation: The telegraph sounder, which relied on the make and break of a circuit to produce an audible click, was the earliest form of electric signal, predating the telephone and wireless communication.
What is the approximate range of pitch for the human voice?
- 32 to 128 vibrations per second
- 87 to 768 vibrations per second
- 128 to 1,024 vibrations per second
- 256 to 2,048 vibrations per second
Correct Answer: 87 to 768 vibrations per second
Correct Answer Explanation: The range of pitch for the human voice, encompassing the fundamental frequency and its harmonics, is approximately 87 to 768 vibrations per second. This range is important for understanding the human voice and its transmission through telephone systems.
In 1910, what percentage of the US population had a telephone?
- 1/10
- 1/12
- 1/15
- 1/20
Correct Answer: 1/12
Correct Answer Explanation: In 1910, approximately one-twelfth of the US population had a telephone, reflecting the growing adoption of this revolutionary technology.
Which of the following is NOT a type of early microphone?
- The Hughes microphone
- The Blake transmitter
- The White transmitter
- The Berliner microphone
Correct Answer: The Berliner microphone
Correct Answer Explanation: While the Berliner microphone was a significant advancement in telephone technology, it was not one of the early types of microphones discussed in the provided text. The Hughes microphone, Blake transmitter, and White transmitter were all early microphones that played a crucial role in the development of telephony.
What was the major advantage of common-battery systems over local battery systems in early telephone systems?
- They were less expensive to install and maintain.
- They provided a more stable and reliable power source.
- They allowed for longer distance transmissions.
- They were more efficient in handling large numbers of calls.
Correct Answer: They were less expensive to install and maintain.
Correct Answer Explanation: Common-battery systems, where the central office supplied the power for all connected telephones, were more cost-effective and easier to maintain than local battery systems, where each telephone had its own battery.
What was the primary reason for the failure of the first automatic switching equipment?
- It was too expensive to implement.
- It was too complex and difficult to maintain.
- It lacked the capacity to handle a large number of calls.
- It attempted to connect every line to every other line directly, which was impractical and unreliable.
Correct Answer: It attempted to connect every line to every other line directly, which was impractical and unreliable.
Correct Answer Explanation: The first automatic switching equipment failed because it was designed to directly connect every line in the central office to every other line. This proved to be too complex and unreliable, leading to the development of more efficient methods, such as trunking.
What is the approximate electromotive force of a Lalande cell?
- 0.5 volts
- 0.67 volts
- 1.0 volts
- 1.5 volts
Correct Answer: 0.67 volts
Correct Answer Explanation: The Lalande cell, a type of battery used for heavy-duty service in early telephone systems, had a constant electromotive force of about two-thirds of a volt, which is approximately 0.67 volts.
What is the typical frequency range of human hearing?
- 16 to 16,000 Hz
- 32 to 32,000 Hz
- 64 to 64,000 Hz
- 128 to 128,000 Hz
Correct Answer: 32 to 32,000 Hz
Correct Answer Explanation: The human ear can perceive sound waves at frequencies ranging from 32 to 32,000 vibrations per second, which is equivalent to 32 to 32,000 Hz. This range is important for understanding the transmission and reception of sound in telephone systems.
What is the approximate mutual electrostatic capacity of a telephone line composed of two wires of .036 inch diameter, wrapped in paper and twisted into a pair, per mile?
- 0.04 microfarads
- 0.08 microfarads
- 0.12 microfarads
- 0.16 microfarads
Correct Answer: 0.08 microfarads
Correct Answer Explanation: A telephone line composed of two wires with a diameter of .036 inch, wrapped in paper and twisted together, has a mutual electrostatic capacity of approximately 0.08 microfarads per mile. This is an important parameter in understanding the electrical properties of telephone lines and how they affect signal transmission.
What is the approximate number of independent telephones installed in the United States by the early 1910s?
- 1.5 million
- 3.9 million
- 5.5 million
- 7.2 million
Correct Answer: 3.9 million
Correct Answer Explanation: By the early 1910s, independent telephone companies in the United States had installed nearly 3.9 million telephones. This number reflects the rapid growth and competition in the telephone industry during this period.
What was the primary function of the induction coil in early telephone systems?
- To amplify the sound waves picked up by the microphone.
- To convert the electrical signals from the microphone into sound waves.
- To increase the voltage of the signal, reducing losses and allowing transmission over longer distances.
- To filter out unwanted frequencies from the signal.
Correct Answer: To increase the voltage of the signal, reducing losses and allowing transmission over longer distances.
Correct Answer Explanation: The induction coil, essentially a transformer, was crucial for transmitting sound over long distances in early telephone systems. It increased the voltage of the signal, reducing losses and allowing for greater transmission distances.
What is the typical range of fundamental frequencies for the human female speaking voice?
- 85 to 160 vibrations per second
- 150 to 320 vibrations per second
- 250 to 500 vibrations per second
- 500 to 1,000 vibrations per second
Correct Answer: 150 to 320 vibrations per second
Correct Answer Explanation: The typical range of fundamental frequencies for the human female speaking voice is between 150 and 320 vibrations per second. This range is essential for understanding the characteristics of the human voice and its transmission through telephone systems.
Which of the following is NOT a type of telephone transmitter?
- The Blake transmitter
- The White transmitter
- The Acousticon transmitter
- The Bell transmitter
Correct Answer: The Bell transmitter
Correct Answer Explanation: The Bell transmitter was actually the original type of telephone transmitter, invented by Alexander Graham Bell. However, it was later replaced by more efficient designs, such as the Blake transmitter, the White transmitter, and the Acousticon transmitter. These newer transmitters offered improved sensitivity, power, and clarity.