1. Beath High School - Int 1 Physics
Intermediate 1 Physics
Electronics
Questions
and
Answers
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2. Beath High School - Int 1 Physics
Intermediate 1 Physics
Electronics
Q 1 to 9
Q 10 to 18
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3. Beath High School - Int 1 Physics
Electronic Systems
1. Describe what is meant by an electronic system. Give two examples
An electronic system is made up from lots of electronic components to do a particular job.
Two examples of electronic systems are a calculator and a public address system.
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2. The block diagram for a calculator is shown below. Identify the input, process and output subsystems.
Input
Process
Output
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3. Draw a block diagram of each of the following systems. Identify the input, process and output subsystems in each case.
(a) A public address system
(b) A smoke alarm
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(c) An automatic porch light (lamp lights when it gets dark)
(d) An automatic fan (fan operates when it gets too warm)
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(e) A radio.
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4. What is sensed by each of the following input devices
(a) microphone
sound
(b) thermistor
heat
(c) light dependent resistor
light
(d) switch
pressure
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5. What can change the resistance of a thermistor?
Change in temperature
6. State how the resistance of a light dependent resistor changes with light level.
As the light level increases the resistance decreases
7. Describe an experiment you would perform to determine how the resistance of a thermistor changes with temperature.
Connect a thermistor to a resistance meter and heat the thermistor gently with your fingers. Watch what happens to the resistance on the meter.
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8. Describe an experiment you would perform to determine how the resistance of a light dependent resistor changes with light level
Connect a LDR to a resistance meter and cover it over with your hand. Watch what happens to the resistance on the meter.
9. Describe how you would use an oscilloscope to examine the output signal from a microphone. Describe what is seen on the oscilloscope screen.
Connect the microphone to the input of the oscilloscope. Speak into the microphone. You will see a wave pattern on the screen which matches your voice.
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10. Describe the energy changes which take place in the following output devices:
electrical energy to sound energy
loudspeaker
electrical energy to sound energy
buzzer
electrical energy to light energy
lamp
light emitting diode (LED)
electrical energy to light energy
electrical energy to kinetic energy
electric motor
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11. Study the circuit symbols below. In each case:
(a) name the device
(b) state whether it is an input or output device
(c) state the energy changes in the device
(d) give an example of where it could be used
(a) microphone
(b) input device
(c) sound energy to electrical energy
device 1
(d) input to a public address system
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(a) buzzer
(b) output device
(c) electrical energy to sound energy
device 2
(d) warning device on a freezer, if temperature inside rises above a particular temperature
(a) motor
(b) output device
(c) electrical energy to kinetic energy
(d) output for a room cooling system
device 3
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(a) thermistor
(b) input device
(c) heat energy to electrical energy
device 4
(d) input device on a freezer, to check temperature inside does not rises above a particular temperature
(a) light emitting diode
(b) output device
(c) electrical energy to light energy
(d) indicates that something is switched on
device 5
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(a) lamp
(b) output device
(c) electrical energy to light energy
device 6
(d) output device for an automatic light which switches on when it gets dark
(a) loudspeaker
(b) output device
(c) electrical energy to sound energy
(d) output device for a radio, so that we can hear the music.
device 7
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(a) light dependent resistor
(b) input device
(c) light energy to electrical energy
device 8
(d) input device for an automatic light which switches on when it gets dark
12. In the applications below identify which of the devices in Q 11 would be suitable.
Give a reason for the choice of each device.
(a) Output of a radio
Loudspeaker, it changes the electrical energy form the amplifier to sound energy
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(b) Input of an automatic lamp
LDR, because its resistance changes as the light level changes
(c) Input of a heating controller
Thermistor, because its resistance changes as the temperature changes
(d) Output of a fan
Motor, because it will turn the fan.
(e) Output of an electronic timer
Light emitting diode, it can form the part of a seven segment display to show the numbers.
(f) Input of a cassette recorder – recorder subsystem
Microphone, it will pick up the sound to be recorded.
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(g) Output of a cassette recorder – drive subsystem.
Motor, it will turn the spindles.
(h) Output of a cassette recorder – play back system
Loudspeaker, it will change the electrical energy back into sound energy.
13. Describe what is meant by a “digital signal”.
A digital signal is either on or off
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14. Draw an oscilloscope trace of a digital signal
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15. Draw the symbol for each of the following logic gates:
(a) NOT gate or Inverter
(b) AND gate
(c) OR gate
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16. The following is a truth table for a logic gate.
Input
Output 1
(a) Name the logic gate.
A NOT gate or inverter
(b) Explain in terms of voltage levels, what is meant by the “1”s and “0”s.
“1” is a high voltage, “0” is a low voltage
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17. For each of the logic gates shown below:
(a) Name the gate
(b) Draw the truth table
(c) Describe the operation of the gate in words.
Gate 1
(a) NOT gate or inverter
Input
Output 1
(b)
(c) The output of the NOT gate is always the opposite of the input
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Gate 2 A B
(a) AND gate
Input B
Output 1
(b)
Input A
(c) The AND gate combines the input signals so that the output is only 1 when both inputs are 1.
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Gate 3 A B
(a) OR gate
Input B
Output 1
(b)
Input A
(c) The output of an OR gate is ‘1’ when any input is ‘1’.
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18. The system below is designed to allow water to be sprayed on to plants if the air becomes too hot or the gardener switches the sprayer on.
Heat sensor
1 = hot
0 = cold
Motor to operate sprayer
switch A B
(a) Name the logic gate used in the system.
OR gate
(b) The gardener switches the the sprayer on. What is the logic level at B?
Logic 1
(c) What input device could be used in the heat sensor?
Thermistor
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Intermediate 1 Physics
Electronics
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Questions and
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