February 2025

Coal as a fuel

By |2025-02-12T09:03:21+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Coal Mining at Hwange. Image credit chronicle.co.zw Coal Mining at Hwange. Image credit chronicle.co.zw ZIMSEC O Level Combined Science Notes: Coal fuel

  • Coal is a common solid fuel
  • It is a non-renewable resource
  • It is used as a raw material by industries such as at ZISCO and less commonly as a […]
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Social and economic factors to consider when using fuels

By |2025-02-12T09:16:45+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Oil spills are destructive to vegitation. Image credit africanewscircle.com Oil spills are destructive to vegetation. Image credit africanewscircle.com ZIMSEC O Level Combined Science Notes: Social and economic factors to consider when using fuels

  • The extraction and consumption of fuels has led to a lot of problems in recent years
  • Problems include:

    • […]

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Perfecting the electric cell

By |2025-02-12T09:34:36+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Polarisation in a simple cell Polarisation in a simple cell ZIMSEC O Level Combined Science Notes: Perfecting the electric cell

Voltage/Potential difference

  • The voltage between the two electrodes is dependent on the type of electrode used
  • When magnesium and copper are used the potential difference between the two electrodes is fairly high

    • […]

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Transmission of electricity

By |2025-02-12T08:59:46+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The Power Grid. Image credit source.co.zw The Power Grid. Image credit source.co.zw ZIMSEC O Level Combined Science Notes: Transmission of electricity

  • At Hwange, Kariba, Munyati and other places AC power is generated
  • This is because the most efficient power generators produce AC power
  • In addition to that AC power can be […]
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Experiment: Comparing roof truss structures

By |2025-02-12T09:15:47+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

A bridge made of ice cream sticks. Image credit pinterest.com A bridge made of ice cream sticks. Image credit pinterest.com ZIMSEC O Level Combined Science Notes:Experiment: Comparing roof truss structures

Aim:  To determine which structure is best for roof trusses/bridge girders

Materials:  Poplar wood /ice cream sticks/grass straws, stikistuff/drawing pins/glue, tin of sand, […]

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Arch bridges

By |2025-02-12T09:30:24+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

An arch bridge An arch bridge ZIMSEC O Level Combined Science Notes: Arch bridges

  • In an arch bridge the arch acts to support a load by converting the downward force into sideways thrust
  • Arches can make structures last longer for example old buildings and structures in European countries have lasted as […]
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Pumps: Blair pump

By |2025-02-12T09:05:51+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The blair pump The blair pump ZIMSEC O Level Combined Science Notes: Pumps: Blair pump

  • The pumped was first developed in 1976
  • The design was further refined at the Blair Research Laboratory in Harare
  • Various models have been subsequently designed and made
  • Cumulating in the famous Type B bush pump
  • It is popularly known […]
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Introduction to diseases

By |2025-02-12T09:25:32+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Parirenyatwa entrance. Image credit financialgazette.co.zw Parirenyatwa entrance. Image credit financialgazette.co.zw ZIMSEC O Level Combined Science Notes: Introduction to diseases

  • A disease is an illness
  • Diseases are caused by pathogens
  • Pathogens come in the form of:
  • bacteria, viruses, fungi, protozoa(single celled animals) and small worms
  • Bacteria can be viewed using a light microscope

    • […]

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Contraception: The use of spermicides

By |2025-02-12T09:43:53+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Couple having dinner. Image credit singleblackmale.org Couple having dinner. Image credit singleblackmale.org ZIMSEC O Level Combined Science Notes:Contraception:Ways to prevent pregnancy

  • Spermicides are sperm killing chemicals

How it works

  • Are usually in the form of jelly cream placed into the vagina before sexual intercourse
  • The chemical kills spermatozoa

Effectiveness

  • 60-95%

Advantages

  • Does not require […]
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Protecting Water supplies

By |2025-02-12T09:10:19+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

A protected well. Image credit totallandcare.org A protected well. Image credit totallandcare.org ZIMSEC O Level Combined Science Notes: Testing the purity of water

  • Most rural areas do not have access to running tap water
  • Their water comes from various sources including dams, wells, boreholes, springs
  • Some of these sources are produce […]
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