Download File - Edward Burns Biology/Science

Measurement
Quantity
Length
Mass
Time
Area
Volume
SI unit
Metre
Kilogram
Second
Square metre
Cubic metre
Quantity
Length
Measured with
Trundle wheel
Opisometer (curvy lines )
Metre stick
Tape
Balance
Stop clock
Graph paper
Formula length x breadth
Measuring Cylinder
Overflow can
Formula length x breadth x
width
Mass
Time
Area
Volume
Symbol
m
Kg
S
M2
M3
Know experiments to measure volume
Mass is the amount of matter in an object. It is measured in Kg
Density is the mass if 1cm3 of a substance. It is measured in g/cm3
Density =
Mass
Volume
An object floats because its density is less than that of the liquid it is in. An object will
sink because its density is greater than that of the liquid it is in.
A force is anything that causes an object to move. It can be a push or a pull. Forces
always occur in pairs.
Hookes Law
When a force is applied to the end of a string it will cause it to extend. The increase in
length is proportional to the force applied to it.
Learn experiment 41.2 on page 277
Friction
Friction is the force which prevents easy movement between two objects in contact
Advantages of friction: Makes it easier to stay standing or walking
Disadvantages: Friction can cause things to wear out quickly
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To reduce friction you use lubrication(grease)
Work is done when a force moves an object
Work = force x distance
Energy
Energy is the ability to do work. It is measured in Joules
There are eight forms of energy
Potential energy ( stored energy) eg in a spring or due to height
Kinetic energy – moving things
Heat
Light
Sound
Electrical
Chemical (battery)
Nuclear
Law of conservation of energy
Energy cannot be created or destroyed only converted from one form to another.
Energy can be renewable ( can be replaced) or non renewable ( cant be replaced)
Renewable = solar, hydroelectric, wind, wave, biomass (from plants), geothermal ( the
heat from the earths surface)
Non renewable = the fossil fuels – coal , oil, gas, peat
The sun is the primary source of all energy on earth
Power is the rate at which work is done. It is measures in Watts
Power =
Work done
Time
Weight
Wieght is a force and is measured in Newtons N. It is the force of gravity acting on an
object
Weight = Mass x gravity
Weight = mass x 10 (on earth)
We weigh less on the moon because gravity on the moon is less. But our mass
everywhere is the same.
Levers
A lever is a rigid body which is free to turn about a fixed point called a fulcrum
Moment of force = force x perpendicular distance
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When a lever is balanced the moments of force are equal. The moments on the right = the
moments on the left
The effort on a lever is where the force is applied
The load is where the force takes effect.
Centre of gravity
Of a sheet of cardboard
Hang sheet freely.Draw a vertical line on the cardboard
Hang sheet from a different position and draw vertical line.
Repeat for different positions. The centre of gravity is where all the lines intersect.
Objects:
If objects are stable they have a low centre of gravity eg a wide base
If objects are unstable they have a high centre of gravity – eg narrow base with wide
top
If objects are neutral their centre of gravity is in the middle eg a ball
Pressure
Pressure is the force per unit area and it is measured in Pascals P
Pressure = Force
Area
Stiletto heels on shoes make marks in the floor because all the weight of you body is on
the heel, which has a small area so there is great pressure. If you are wearing flat shoes
the body’s weight is distributed over the whole area of the sole so the pressure is less
When people go diving the have to come up slowly to prevent getting the bends as a
result of the pressure changing with depth.
To show atmospheric pressure boil water in a can close the lid and cool the can quickly
and it will collapse in due to the atmospheric pressure pushing on it.
Atmospheric pressure is measured using a barometer.
Altitude ( height) is measured using an altimeter
Pressure and the weather
Pressure on maps for the weather is measured in isobars. High pressure means good
weather, low pressure means bad weather.
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Electrostatics
1:
Atoms contain the same number of protons (+ charge) and electrons (- charge),
and are therefore electrically neutral. It is sometimes possible to give some substances a
charge by adding or removing electrons, e.g. polythene rubbed with a cloth gains
electrons and becomes negatively charged. Perspex rubbed with wool looses electrons
and becomes positively charged.
2:
Like charges repel and unlike charges attract.
Magnetism
1.
Like poles repel and unlike poles attract.
2.
A magnetic field is the region around a magnet where a magnet exerts influence.
Current electricity
1. Electricity is a form of energy and it may be converted to other forms of
energy. Electric current flows from +ve to -ve, though the electrons flow
from –ve to +ve.
2. Units.
The Ampere (A) is the unit of electric current. This can be measured by an ammeter
which is placed in series in the circuit.
The Volt (V) is the unit of potential difference. This can be measured by a voltmeter
which is placed in parallel in the circuit.
The Ohm (  ) is the unit of resistance.
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The Watt (W) is the unit of power.
3.
Relationship between voltage, current, resistance and power.
Ohms Law: At constant temperature, the current flowing through a resistor is
proportional to the potential difference across the resistor. Learn the experiment
V/I=R
The power generated by an appliance is equal to the voltage multiplied by the
current W=VI.
4.
The E.S.B. charge by the unit of electricity used. 1 unit = 1 kilowatt hour. This is
the quantity of electricity used when a 1 kilowatt appliance is used for 1 hour.
5.
In an electric circuit a fuse is fitted as a safety device. If too high a current flows, the
fuse melts and stops the current flowing in the circuit.'
6.
Electric current is the flow of electrons through a material. A conductor allows
electric current to flow and an insulator does not allow electric current to flow.
7:
Effects of an electric current.
Heating effect
To demonstrate this, pass a current through a wire that has a high resistance. The wire
heats up. Applications include: electric heater, electric kettle, immersion heater.
Chemical effect
(i) Electrolysis of water is the splitting of water into its elements, hydrogen and
oxygen, in a Hoffmann Voltameter, by an electric current.
(ii) Electroplating is covering a metal, e.g. iron, with a second metal, e.g. chromium.
It is used to protect one metal or to coat one metal with a more expensive one, e.g.
silver plating.
Magnetic Effect
The magnetic effect of an electric current can be demonstrated using a large current
carrying wire and a magnet The magnetic effect of a solenoid can be shown using a
current carrying solenoid and a plotting compass
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9:
Domestic Wiring
The 3 pin plug connects an appliance to the electricity supply.
(i) The earth wire - colour Yellow/Green. If a fault develops the current travels
to earth and the fuse blows, stopping the flow of current.
(ii) The live wire - colour brown - carries the current. It also has the fuse.
(iii) The neutral wire - colour blue
The sockets and lights are connected in ring circuits in the house.
A radial circuit is used for something like a cooker which uses a lot of power.
A spur is a method of adding extra sockets, one spur per socket in the ring. The light
switch is always connected to the live wire.
Older houses have a fuse board and more modern houses or houses that have been
rewired have circuit breakers which switch off the current if it goes above a certain value.
10:
series and parallel
If light bulbs are connected in series when 1 goes they all go. The more light bulbs you
add the dimmer they all get.
For resistors in series Rtotal = R 1 + R 2 + R3
R1
R2
R3
Resistors in parallel. This is a better way to wire your light circuits because when one
light bulb goes the others stay lighting unlike like light bulbs in series.
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Resistors in parallel
11.
Direct current (D.C.) always flows in one direction. Alternating current
(A.C.) changes direction many times a second. In the mains electricity it
is 50 cycles per second. AC may be changed to DC by means of a
rectifier.
Light and sound
1.
Light is a form of energy.. Show using a Crookes radiometer page 328
2.
White light is made up of seven colours, red, orange, yellow, green, blue, indigo,
violet. (Mnemonic: Ring Out Your Great Bells In Victory)
3.
Dispersion occurs when white light is broken up into its component colours. This
occurs when light is passed through a prism or a diffraction grating.
4.
Light can be reflected from a surface.
5.
Light travels in straight lines.
Shadows are formed when an object gets in the way of light which is traveling in straight
lines
Luminous objects are objects that give out light ( anything that glows in the dark)
Non luminous objects absorb light.
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9:
Reflection is when light bounces back off surface
10: A simple periscope uses reflection to work
11:
Refraction is the bending of light rays when they go from one medium to another,
e.g. air to water.
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12.
A convex lens causes light to converge and a concave lens causes
light to diverge.
CONVEX LENS
CONCAVE LENS
Convex lenses are used in magnifying glasses to make things bigger.
13.
Sound is a form of energy. It needs a medium to travel. Remember the
bell in the bell jar. When the air is pumped out you cannot hear the sound as
there is no medium in which the sound can travel
The velocity or speed of sound in air is 331 m/s. It is measured using the
formula
Speed = distance
Time
Reflection of sound is called an echo.
Reflection of sound is also used in ultrasound – finding fish or when you are
pregnant
Light travels much faster than sound that is why you see lightening before you
hear the thunder.
Sound travels at different speed depending on the density that is why you
sound different if you talk after inhaling helium gas or carbondioxide. It also
explains why you hear sounds clearer on a cool night.
Sound is measured in decibels. Noise should not be greater than 85decibels
otherwise your hearing could be damaged. The loudness of sound can be
measured using a soundmeter
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Light Experiments
1:
Light is a form of energy
Use a crookes radiometer
2:
Light travels in straight line
Use cards with pin holes in them and string
When all the holes are in a straight line you can see light
Sound Experiments
1:
Sound needs a medium to travel in
Use bell in a bell jar
2:
Sound can be reflected
Use ticking clock and two tubes
Adjust tube until clock is heard at its loudest
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Heat
1:
Heat is a form of energy. It is measured in joules
2:
Heat movement
1:
Conduction
2:
Convection
3:
Radiation
the transfer of heat through a solid
the transfer of heat through a liquid
is the movement of heat through electromagnetic rays
3: The temperature of a body is a measure of how hot a body is.
4:
Temperature is measured using a thermometer.
Two types of thermometer are an alcohol thermometer and a mercury thermometer.
Mercury thermometer
Alcohol thermometer
Less sensitive than alcohol thermometer
more sensitive than mercury thermometer
Easy to use
dye needs to be added to see it
range -39° to 350°C
-140°C to 75°C
5:
Black surfaces radiate and absorb heat more efficiently than shiny surfaces.
6:
An insulator prevents heat loss by conduction, e.g. clothes, double glazing,
vacuum flask. The tog value tells us how good an insulator is a certain material, e.g. a tog
value is found on duvets.
7:
Solids, liquids and gases expand on heating and contract on cooling.
The bimetallic strip consists of two metals bonded together one of which expands more
than the other on heating. It therefore bends on heating. It is used in fire alarms and in
thermostats.
8:
Water expands by approx. 9% of its volume on freezing and so it may damage
pipes and car engines when it freezes.
9:
Latent heat is the heat absorbed or released when a material changes state without
a change in temperature.
10:
Increase in pressure raises the boiling point of a liquid and decrease in pressure
lowers the boiling point of a liquid. Increased pressure lowers the melting point of
a solid
11:
Sublimation occurs when a solid is heated and it changes directly to a gas without
going through the liquid state, e.g. dry ice, iodine, ammonium chloride.
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Electronics
LED = light emitting diode
These are all the small green or red lights that you see on electrical appliances
LDR = light dependant resistor
LDR are used to turn street lights on automatically at night, The are also used in alarm
sensors which goes off when you break a beam of light
Diodes
Diode allows current to flow in one direction only
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Science - Revision Planner
TOPIC GUIDE
Physics
**
Motion
Forces
Energy
Heat
Magnetism
Electricity
Waves
Light
Sound
Core of Earth Science
Chemistry
**
Matter
Mixtures
Gases: oxygen, carbon dioxide, air
Atomic structure and bonding
Chemical equations
Water
Acids, bases, salts
Metals
Electrochemistry
Biology
**
Cells – plant and animal cells
Human biology
Photosynthesis
Respiration
General plant biology
Ecology
Soil
Microbiology
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REVISED