Grade 9 Technology Project Term 3 Mini PAT Questions and Answers
Mini PAT 1: Situations where electronic circuits control electric circuits
An electronic circuit is different from an electric circuit because it only uses a very small current, and because it uses electronic control devices such as thermistors, LDRs, diodes and transistors.
There are many household appliances that use electronic circuits to control electric circuits with bigger currents.
The following two devices are used inside the electric switchboard (or distribution board) of every building that is connected with electricity in a safe way.
- Ordinary circuit breakers: Shuts off a circuit (for example the circuit supplying all the lights in a house) when the current becomes too big (if the current is too big for the thickness of wire used, the wire will overheat).
- Residual-current circuit breakers: Switches off the main power supply if it detects a leakage of power, such as when a person accidentally touches a “live” electrical wire or contact and the electricity is then conducted through his or her body. This device has to cut the current very quickly; otherwise the person can die due to electric shock. Therefore it switches off the power even when it detects only a small amount of leakage of electrical current.
The following household appliances use electronic circuits to control them:
- ovens: to control the temperature,
- radios and other music appliances: to control the volume of the speakers,
- some energy-saving lights: to switch off automatically when there is enough natural light, and
- kettles: to switch off when the water boils.
Questions:
- Give two examples of situations or applications where electrical circuits are used.
- Give two examples of situations or applications where electronic circuits are used.
- Give three examples of situations or applications where electronic circuits and electric circuits are used together.
Give two examples of situations or applications where electrical circuits are used Answers:
Electrical circuits are used in a wide variety of applications, from simple household appliances to complex industrial equipment. Here are two examples of situations or applications where electrical circuits are commonly used:
- Lighting: Electrical circuits are used to power lighting in homes, offices, and public spaces. The circuit typically consists of a power source, such as a battery or mains electricity, connected to a switch and a series of light fixtures. When the switch is turned on, the circuit is completed, and electricity flows through the circuit to power the lights.
- Computing: Electrical circuits are a critical component of computers and other electronic devices. The circuitry in these devices includes components such as microprocessors, memory chips, and input/output devices, all of which are connected by circuits that allow for the flow of electricity. These circuits are responsible for carrying out the complex calculations and data processing that enable computers to perform their various functions.
Give two examples of situations or applications where electronic circuits are used Answers:
Electronic circuits are used in a wide range of applications, from small electronic devices to large industrial machines. Here are two examples of situations or applications where electronic circuits are commonly used:
- Consumer Electronics: Electronic circuits are used in a wide range of consumer electronic devices such as mobile phones, televisions, and computers. These circuits are responsible for processing and transmitting signals, powering the device, and controlling the device’s various functions. For example, a smartphone’s electronic circuits are responsible for processing data from the phone’s sensors, powering the phone’s display, and managing the phone’s battery life.
- Industrial Automation: Electronic circuits are also used in industrial automation applications, such as robotics and process control systems. These circuits can be used to control the movement of machines, monitor production processes, and ensure worker safety. For example, electronic circuits can be used to control the movement of robots in an automated factory or to monitor the temperature and pressure of a chemical process in a manufacturing plant.
Give three examples of situations or applications where electronic circuits and electric circuits are used together Answers:
Electronic and electric circuits are often used together in a variety of applications to provide a complete solution. Here are three examples of situations or applications where electronic circuits and electric circuits are used together:
- Home automation: In a home automation system, electronic and electric circuits work together to control various functions such as lighting, heating, and security. The electric circuit provides power to the system, while the electronic circuits process data from sensors and user inputs to control the system’s functions.
- Medical devices: In medical devices such as heart monitors, electronic and electric circuits work together to measure the electrical signals generated by the heart and provide information to medical professionals. The electric circuit provides power to the device, while the electronic circuits process and amplify the electrical signals generated by the heart.
- Automotive systems: In modern cars, electronic and electric circuits work together to control various systems such as the engine, transmission, and infotainment systems. The electric circuits provide power to the various systems, while the electronic circuits process data from sensors and user inputs to control the various functions of the car.
Mini PAT 2: Investigate: A circuit with an input sensor, control knob, transistor and output device.
A sensor is a control device that can have a variable effect. A switch can only be open (infinitely large resistance) or closed (zero resistance), so a switch is not a sensor. Devices such as thermistors and LDRs can have different resistances, depending on the temperature or amount of light. They can therefore be used as sensors. A device that can generate a voltage, such as a photovoltaic cell, can also be used as a sensor. A sensor “senses” something such as temperature, or light, just as your body’s senses do. A variable resistor is also a control device, but it is not a sensor, because it is a device for which the user can set the resistance.
The circuit for the fire alarm that you built in Chapter 5 can be used for different applications where a small input current from an input sensor has to switch on a circuit with a larger current for an output device. There is also a variable resistor so that the user can determine at what level of light or temperature (for example) the output device should be switched on or off.
Questions:
- Name three input components that you know of.
- Name three output devices that you know of.
- Name a device that uses a control knob to set the level of something.