January 2023

Science:Lighting

By |2022-09-15T12:38:49+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

Lightining is a result of electrostatic discharge. Image credit zmescience.com Lightining is a result of electrostatic discharge. Image credit zmescience.com ZIMSEC O Level Combined Science Notes: Conductors and insulators

  • Clouds are poor conductors because they are made of mostly water particles
  • They may become charged due to friction forces within them […]
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Lightning and safety

By |2022-09-15T12:38:48+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

Lightning conductors in action. Image credit ask.com Lightning conductors in action. Image credit ask.com ZIMSEC O Level Combined Science Notes: Lightning and safety

  • Lightning has very high voltages
  • It can electrocute, maim or kill a person if they are struck
  • Several precautions can be taken to prevent this from happening:
  • People […]
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Current electricity

By |2022-09-15T12:38:48+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

A simple circuit diagram A simple circuit diagram ZIMSEC O Level Combined Science Notes: Current electricity

  • When electricity flows from one point to another through a conductor this is known as electric current
  • Electric current when electricity flows from one point to another through a conductor
  • If an electric cell is used

    • […]

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Potential difference

By |2022-09-15T12:38:47+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

A voltmeter in a circuit A voltmeter in a circuit measuring potential difference between two points ZIMSEC O Level Combined Science Notes: Potential difference

  • Potential difference is the “electrical pressure” which causes current to flow in a circuit
  • The amount of current flowing depends on the potential difference of the circuit

    • […]

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Experiment: Finding the resistance of a resistor using a voltmeter

By |2022-09-15T12:38:45+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes:  Experiment: Finding the resistance of a resistor using a voltmeter

Aim:  To find the resistance of a resistor in a circuit using voltmeter

Materials: cells, ammeter, resistor,switch, leads with crocodile clips

Finding Resistance

Method

  1. Set up the circuit as shown above
  2. Close the switch
  3. Read and record values of the […]
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Resistors in parallel and in series

By |2022-09-15T12:38:45+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

fusion_title size=”3″ content_align=”left” style_type=”default” sep_color=”” margin_top=”” margin_bottom=”” class=”” id=””]ZIMSEC O Level Combined Science Notes:  Resistors in parallel and in series [/fusion_title]

  • Resistance in a series can be changed by placing more or less resistors in a circuit
  • The total resistance of resistors depends in the way in which they are arranged in the circuit
  • Resistors can be put in series or […]
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Electrical Power

By |2022-09-15T12:38:43+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Electrical Power

  • Electric power is the rate of doing work or the rate of of using energy
  • Electric power is the rate which an electrical device is converting electrical energy into heat or light or any other form of energy e.g kinetic energy in an electric motor
  • When current flows through a wire some of […]
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Uses of generators

By |2022-09-15T12:38:34+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

Generators have many uses.Image credit wheelerdealers.co.zw Generators have many uses.Image credit wheelerdealers.co.zw ZIMSEC O Level Combined Science Notes:  Uses of generators

  • In Zimbabwe there a number of Power Stations that generate electricity
  • In practice most generators are AC rather than  DC generators
  • At Kariba there is a Hydro Electric station

    • […]

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Transmission of electricity

By |2022-09-15T12:38:34+02:00January 24th, 2023|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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