Short Questions Study Material and Sample Answers_____ C.Campbell 1 St. Mary’s D.S Short Questions...

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C.Campbell 1 St. Mary’s D.S

Short Questions Study Material and Sample Answers

Sign: Meaning:

Flammable Material or Liquid –This means that a material or liquid will catch fire and support combustion easily.

Meeting Point – This is used in the case of evacuation in which this sign is fixed in a safe place so people can gather here.

Face Mask Mandatory – This means that a face mask must be worn in a designated area or when conducting a certain process. Note that id any sign has a blue back ground it means mandatory

Safety Glasses/Goggles Mandatory – This means that a safety glasses/goggles must be worn in a designated area or when conducting a certain process.

Ear Protection Mandatory – This means that a ear muffs or plugs must be worn in a designated area or when conducting a certain process.

Face Shield Mandatory – This means that a face shield must be worn in a designated area or when conducting a certain process.

Danger Blade Rotating - This means that there is a blade rotating at high speed and that you should be cautious and keep your hands at a safe distance

Electrical Hazard- a dangerous condition where a person could make electrical contact with equipment or a conductor and may sustain an injury from shock

Irritant – This means that chemicals will irate your skin and may cause redness or blisters on your skin

Toxic - Can cause death, if swallowed, breathed in or

absorbed by skin

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Technology in Society Common Short Questions

Abbreviation: Meaning:

ROM Read Only Memory

RAM Random Access Memory

USB Universal Serial Bus

CPU Central Processing Unit

VDU Visual Display Unit

WWW World Wide Wed

WEEE Waste Electric Electronic Equipment

CAM Computer Automated Manufacture

CAD Computer Automated Design

Processed Food vs Fresh Food

Processed Food - processed foods are produced using manufacturing methods to transform raw

ingredients into neatly packaged goods, which have a longer shelf life. Processed foods often contain

preservatives, colourings and sweeteners.

Fresh Food - Relates to food in it raw form. An example of this is fruit and vegetables that are grown on

farms. These foods generally have a shorter shelf life and take longer to prepare.

Processed Food

Advantages: Disadvantage:

Longer shelf life

Easy to cook or prepare and sometimes ready to eat

Can be very taste and enjoyable to eat

Very convenient

Low nutritional Value

More Expensive

Contain artificial ingredients like colourings, preservatives and sweeteners that are bad for our health.

They often contain excessive amounts of sugar and salt

Bulky packaging can lead you to believe that you are getting more that you actually are

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Fresh Natural Food

Advantages: Disadvantages:

Very good for you

High nutritional value

High in vitamins and mineral

Short shelf life

Time consuming and difficult to prepare

Less taste than processed food

Technology in Society Symbols

Symbol: Meaning:

Recycle – this symbol is placed on any material that is recyclable

Disposable – this symbol is generally placed on packaging material and it symbolises that the material should be disposed of after use

Non Disposable - this symbol shows that a product should not be disposed of in the normal manner and therefore must be disposed in a correct manner generally by a disposal contractor or recycling centre. Example – Batteries/ Mobile phones.

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Clothing and Fabrics

Natural vs. Synthetic Fabrics/Material

Natural fabrics are made from things that grow -- wool, cotton, flax, hemp, linen, etc. These are generally

used for fine, high quality or traditional clothing. This would be things like dressy suits and jackets. These

materials are more expensive than synthetic fabrics.

Synthetic fabrics are made from petroleum products-- polyester, nylon. They are used to make clothing

generally of low quality. However they are commonly used for sporting cloths such as jerseys as they are

lighter, they retain less sweat and are easier to clean than natural fabric.

Natural: Synthetic:

Wool Leather Rubber Cotton Linen Silk

Polyester Nylon Spandex Lycra

Electronics Revision:

Component: Appearance: Symbol: Function:

Capacitor

Used to Store energy and smoothen out current

Thermistor

Thermistor = Temperature Dependant Resistor – The resistance will change with the temperature.

Variable resistor

Used to change the resistance by twisting the spindle at the top

Reed Switch

Consists of two thin plates in a glass case and when a magnet cones close to the two plates they will connect completing a circuit

Transistor

Amplifies current and acts as an electronic switch

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LDR -Light Dependant Resistor

The resistance of the LDR changes with the light level. High light levels = Low resistance and low light levels =high resistance

Diode

Allows current to flow one way and not the other

LED – Light Emitting Diode

Allows current to flow one way and not the other and when current flows through it lights up

PTM –Push to Make

When the switch is pressed it completes the circuit

PTB – Push to Break

When the switch is pressed it break the circuit

Buzzer

When current flows through a buzzer it omits a bussing sound

Light Bulb

When current flows through a bulb it lights up

Relay

Electronic switch – used to power a second circuit. Works with a magnetic coil that pulls a pin to complete a circuit

Ammeter

Measures the current in a circuit and must always be connected in series

Voltmeter

Measures the voltage/ potential difference in a circuit and must always be connected in parallel

Ohmmeter

Measures the resistance in a circuit and must always be connected in series

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Darlington Pair

Two transistor connected one after the other to give increased amplification and make sensor circuits more responsive

DPDT – Double pole Double throw

Commonly used to turn a motor clockwise and then with the flick of a switch turn it anti clockwise. Also it can be used to power two different circuits with the flick of a switch.

Multimetre: A multimeter is an electronic measuring instrument that combines several measurement functions in one unit. It can be used to measure voltage, current, resistance, and also test diodes and continuity in a circuit.

Circuit Construction: Breadboards:

Breadboards are used to test circuits. Wires and components are simply pushed into the holes to form a completed circuit and power can be applied. One of the main advantages of using a breadboard is that the components are not soldered and if they are positioned incorrectly they can be moved easily to a new position on the board.

Stripboard (veroboard):

Consists of a grid of holes with copper tracks running along it. When power is applied to the board current

will flow along the copper tracks. Electronic components are places into the holes and then soldered to the

copper track.

The red lines on diagram 2 show how some

vertical columns and horizontal rows are

internally connected. When power is applied

to the breadboard current flows along these

internal connections.

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Printed Circuit Boards:

A printed circuit board are generally unique and are created for a specific circuit. The boards are made with

glass reinforced plastic and consist of drilled holes for the electronic components. On the underside of the

board there are copper tracks which allow current to flow between the components. As they are created

specifically for the circuit they are very neat and tide in comparison to other method. In addition to this

they are easy to construct and trouble shoot.

Mechanics:

Mechanism: Diagram: Function/ Description:

Spur Gear

Rotating toothed cog used to transmit motion or torque. Generally used in a gear train to speed up or slow down motion.

Gear Train

Consists of spur gears in mesh. Used to slow down or speed up motion. A gear train can also be used to change the direction of motion.

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Compound Gear

Compound gear is a number of gears fixed together. The two or more gears are generally different sizes but they will rotate at the same speed. Used to slow down, speed up motion.

Bevel Gear

Bevel gears are used to change the direction or the drive by 90 degrees.

Worm and Wheel

The worm consists of screw tread which is in mesh with a wheel. As the wheel rotates it turn the wheel at a greatly reduced speed. This is a failsafe mechanism as the wheel cannot rotate the worm (so it can hold a load)

Fixed Pulley

A pulley is a wheel on an axle that is designed to support movement of a cable or belt along its circumference. A fixed pulley has no mechanical advantages and is often used in hard to reach places like flag poles.

Movable Pulley

Consists of a pulley that moves with the load. This pulley system has mechanical ad vantages of 2 meaning that if you want to lift a load of 200n you will only have to apply a force of 100n however the rope/belt will move twice as far as the load.

Ratchet and Pawl

Consist of a toothed gear with a spring loaded finger. As it rotates the finger will slot into the gear. This allows it to hold a heavy load without slipping and also prevents it from turning backwards

Cam and Follower

The cam and follow transfers rotary motion into linear motion. The cam consists of a shaped disk and as it rotates the follower (Knife point, roller etc..) will move up and down depending on the shape of the cam.

Chain and Sprocket

Used to transfer motion between two axial. Commonly used in bicycles. The chain is much stronger than a belt and also less likely to slip. However it needs to be lubricated to ensure it moves freely and doesn’t rust.

Lever

A ridge body that rotates around a fixed point known as the fulcrum. Used to lift large load with a large mechanical advantage.

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Linkage

Consists of a series of levers connected together. They are used to produce all types of movement. Common ones are the bell crank linkage, reverse motion, and parallel motion linkage.

Materials Processing and Tools

Name: Diagram: Function:

Hacksaw

Used to cut metals and plastics

Tenon Saw

Used to cut wood. Has a brass strip which ensures the Blade is steady thus making it accurate and good for fine joinery. Can only cut to a limited dept.

Piercing Saw

Used for cutting curves profiles in metals and plastics

Coping Saw

Used for cutting curves profiles in wooden materials.

Countersink Bit

Used to cut a conical (cone) shaped hole to allow a countersunk screw sit flush with the top of the surface

Spade Bit

Used for drilling large radius holes with an electrical or pillar drill. Leaves a rough finish and breakout can be an issue

Marking Gauge

Used for marking line along the grain and also the end grain on wooden material/

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Tinsmiths Snips

Used for cutting out soft sheet material such as copper or aluminium. U should cut close to the line as thin material is difficult to file with out bending.

Hot wire cutter

Used for cutting out modelling foam into various shapes. Consists of a hot wire that burns through the foam.

Pop Riveter

Used to permanently fix materials together. Handles are pulled together which closes the rivet thus holding the two pieces together.

Mallet

Used for driving chisels and also for assembling wooden artefacts in a manner that doesn’t damage the material.

Tri square

Used for checking if a materials is square (90degrees) and also for squaring lines around wooden material.

Scriber

Used for drawing lines on metals

Dividers

Used for drawing circles and arcs on metals

File

Used for removing waste materials and smoothening metals and plastics.

Chisel

Used for peering waste material and also for chopping pout mortise joints

Snips

Used for cutting wire and also for moving the insulation from wire

Hammer

Many different types claw hammer and the ball pein are most common. They are general purpose hammer used for driving nails and bending meats.

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Materials

Plastics:

Thermosetting Plastics –these are plastics that can be heated and formed only once. They are generally hard and

strong. If headed a second time they will bend rather than melt or soften. Examples include:

Thermoplastics: these are plastics that can be heated and formed over and over again. These are widely used in

technology for this reason. Examples are acrylic and Perspex.

Metals:

Ferrous Metals are metals that contain iron. These metals are magnetic and will rust. Examples are steel and cats

iron. Examples steel and pig iron.

Non Ferrous Metals are metals that do not contain iron. They are not magnetic and they will not rust. Examples

include copper and aluminium.

Alloys are a mixture of two or more metals. The combination of the metals will create a metal with superior

properties to each of the individual metals. Examples include Brass (copper and zinc) Bronze (copper and tin)

Wood/ Timber

Hardwoods are generally come from deciduous trees (lose their leaves in winter). Hard wood are hander, stronger

and more difficult to work with then softwoods. They are generally more attractive and expensive. Deciduous trees

take up to 100 years to mature making them scarcer than soft woods.

Native Hardwood: - Oak, Ash and Beech.

Non Native:- Mahogany and Teak.

Softwoods generally come for coniferous trees (keep their leaves in winter). They are softer and easier to work with

than hard woods. They are a very light colour in appearance. They mature between 20 and 30 year depending on

climate making them significantly cheaper than hardwoods.

Native – Sitka Spruce and Scots Pine

Non Native – Cedar and Douglas Fir

Manufactured Board these are man made from the processing of timber and timber products. They can be made

from things like saw dust or recycled wood or wood products thus helping forest conservation. One major advantage

is that they come in sheet format meaning they can be significantly wider than a hardwood/softwood plank. In

addition they can have improved water/moisture resistance properties due to the adhesives used in their

manufacture.

Examples

: Plywood (veneers glue together), MDF Medium density fibre board (compacted wood partials glued together)

Chipboard (compacted wood chippings glued together)

Short Questions Study Material and Sample Answers_____ C.Campbell 1 St. Mary’s D.S Short Questions...

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