Communications

1. Running with a letter for someone was found not to be not a very effective way of sending information. The use of light signals to transmit information meant that the message could be transmitted

• A. faster in a coded format
• B. faster in an uncoded format
• C. slower in a coded format
• D. slower in an uncoded format

2. A digital signal is a code using only

• A. the numbers 1 to 10
• B. the alphabet
• C. morse code
• D. '1' s and '0' s

3. The opposite of a digital signal is

• A. a discrete signal
• B. an alternating signal
• C. an analogue signal
• D. a modulated signal

4. Which of these is NOT a digital storage device?

• A. DVD disc
• B. music cassette tape
• C. external hard drive
• D. music CD

5. Which of these methods is not usually used to transmit information?

• A. Light signals
• B. Radio signals
• C. Gamma signals
• D. Electrical signals

6. Which one of these is not an advantage of digital storage of media?

• A. faster retrieval of data
• B. high quality of music / pictures / data
• C. no need for codes
• D. data can be processed and manipulated quickly

7. In a radio transmitter, what would be used to convert sound energy into electrical energy?

• A. A microphone
• B. An earphone
• C. An aerial
• D. An amplifier

8. A loudspeaker is vibrating backwards and forwards. To do this the speaker must be supplied with

• A. an a.c. current
• B. a d.c. current
• C. an a.c. sound wave
• D. a d.c. sound wave

9. Inside the loudspeaker there is always

• A. A coil and a permanent magnet
• B. 2 metal plates and a permanent magnet
• C. A coil and 2 metal plates
• D. a filament and a coil

10. When a radio wave carries a signal, the wave is varied in some way, for example the amplitude is increased and decreased. This is called

• A. variation
• B. modulation
• C. amplification
• D. encoding

These questions are all about a device called a thermionic diode. They are tough!

image from www.cjseymour.plus.com

11. What particles flow from the filament to the anode plate?

• A. protons
• B. neutrons
• C. electrons
• D. atoms

12. Why does the filament need to have a separate low voltage supply?

• A. to charge the filament
• B. to make it hot
• C. to make the metal filament start to melt
• D. to prevent too much current flowing

13. The release of particles from the filament is called

• A. infra-red radiation
• B. alpha radiation
• C. thermionic emission
• D. cathode emission

14. Which of these words correctly describes the positive and negative ends in this experiment?

• A. The plate supply voltage is increased
• B. The anode is closer to the filament
• C. The plate supply voltage is reversed
• D. The filament supply is reversed