AQA Engineering - Section 3 - Recall Test

• Pneumatic System


  A fluid powered system, using compressible air, used in food processing applications. Can operate quite fast.
• Hydraulic System


  A fluid powered system, using oil or water, to lift heavy loads. Can operate quite slow.
• Monocoque structure


  A structure that supports the load required using an external skin or shell. E.g. Formula 1 car
• Space frame structure


  A truss like structure constructed from struts that lock together. E.g. Roof structure at Trinity Leeds
• Tensile Stresses


  Stresses that occur as a result of pulling forces.
• Compressive Stresses


  Stresses that occur as a result of pushing forces.
• Diode


  A component that allows current to flow in one direction only, from anode to cathode.
• Capacitor


  A component that stores electrical charge. Can you draw the symbol and label it?
• LED


  An output device that produces light when current flows from anode to cathode. Can you draw the symbol and label it?
• Field Effect Transistors


  A digital device for voltage amplification. Used for motors and solenoids. Can you draw the symbol and label it?
• Transistor

  An analogue device for current amplification. Used for lamps and buzzers. Can you draw the symbol and label it?
• Microcontroller


  A small programmable computer on an IC, used for control applications. Can you recall the different FLOWCHART steps?
• Comparator


  An electronic circuit that compares two different input signals. Can you think what the IC would be?
• Counting Circuit


  An electronic circuit that counts the number of times that an event occurs. Can you think what the IC would be?
• Timer Circuit

  An electronic circuit that turns an output device on or off for a set period of time. Can you think what the IC would be?
• Digital Signal


  A signal that is either high (1) or low (0). E.g. MP3 files, Computer networks.
• Analogue Signal


  A signal that varies continuously within a given range. E.g. Sound waves, light levels. Can you draw a quick sketch?
• Stepper Motor


  Output device where full rotation needs to be divided into equal steps. E.g. Robot arms
• Servo Motor


  Output device where precision and speed or positioning is required. E.g. RC Cars
• Solenoid


  Output device that converts electrical energy into mechanical movement, usually linear.
• LDR


  Analogue input that changes resistance, depending on the light levels. Can you draw the symbol for it?
• Micro-switch


  Input device used for detection control applications.
• Direct Current


  Current that flows in one direction. E.g. Batteries
• Alternating Current


  Current that changes periodically. E.g. Mains Voltage
• Bearings


  Used to control motion and reduce friction between moving parts.
• Pulley System


  A mechanical systems using a belt or rope to transmit drive and reduce effort when lifting objects.
• Dwell


  When the follower remains stationary on a cam and follower mechanism.
• Cam and Follower


  A mechanism that converts rotary motion into reciprocating motion.
• Chain and Sprocket


  A mechanism that transmits rotary motion and drive using a chain and toothed wheel.
• Rack and Pinion


  A mechanism that converts rotary motion into a linear motion.
• Bell Crank Linkage


  Has one fixed pivot and two moving pivots. The output movement is at 90 degrees to the input movement. E.g. Crank and slider mechanism.
• Parallel Motion Linkage


  Has two fixed pivots, the rest are moving pivots. E.g. Tool Box Drawer
• Reverse Motion Linkage


  Has one fixed pivot and two moving pivots. E.g. Scissor Jack
• Flowchart


  A diagram that shows the order and flow of operations in a system.
• Output


  Changes the signal from the process sub-system back into a real world signal.
• Process


  Changes the signal in some way, such as counting or timing. E.g. Microcontroller, 555 Timer
• Input

  Turns real world signals into a signal that the process sub-system can understand. E.g. LDR, PTM, Thermistor
• Schematic


  A drawing of a circuit that shows the individual components required and how they are connected together.
• Relay


  Electrically operated switch used to switch a large load load current from a much smaller control current.

  
• Buzzer


  Output device to produce sound