February 2025

Stress in beams

By |2025-02-12T09:12:11+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Types of stresses that affect beams. The arrows show the direction of force. Types of stresses that affect beams. The arrows show the direction of force. ZIMSEC O Level Combined Science Notes: Stress in beams

  • If a material (beam) is subjected to a force, an equal force acts in the opposite direction
  • This […]
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Internal Sources of finance

By |2025-02-12T09:26:52+02:00February 12th, 2025|Notes, Ordinary Level Notes|

Business can make use of internal sources of finance. Image credit elfidental.com Business can make use of internal sources of finance. Image credit elfidental.com ZIMSEC O Level Business Studies Notes: Internal Sources of finance

  • These are funds that can be raised from within the business
  • Internal sources of finance include:
  • Funds raised through […]
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Experiment: Reducing Copper oxide with carbon

By |2025-02-12T09:46:06+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment: Reducing Copper oxide with carbon

Aim: To reduce copper oxide with carbon

Materials: black copper oxide, tongs, crucible lid, powdered carbon, burner

Carbon can be used to reduce copper oxide Carbon can be used to reduce copper oxide

Method

  1. Mix the copper oxide and powdered carbon together in the crucible […]
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Experiment: Determining how concentration affects rates of reaction

By |2025-02-12T09:14:48+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The rate of reaction increases with an increase in concentration The rate of reaction increases with an increase in concentration ZIMSEC O Level Combined Science Notes: Experiment: Determining how concentration affects rates of reaction

Aim: To find the effects of concentration on the rate of reaction using hydrochloric acid and sodium thiosulphate

Materials: 250cm3 beaker, […]

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Experiment: Reduction of copper using carbon

By |2025-02-12T09:30:04+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Extraction of copper from oxides

Aim: To investigate the reduction of copper oxide using carbon

Materials: copper oxide, anhydrous sodium carbonate, charcoal block, blow pipe, burner

The reduction of copper using carbon. Image credit chemistrydemos.co.uk The reduction of copper using carbon.

Method

  1. Mix a little copper oxide with sodium carbonate
  2. Place […]
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Fuel efficiency

By |2025-02-12T09:11:15+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Fuel efficiency

  • Fuel efficiency measures the amount of energy that can be obtained from a given quantity of fuel
  • It is often useful to know which fuel gives the most energy(heat) per given unit
  • In a laboratory fuel efficiency can be determined by measuring the temperature rise of water when it is […]
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Ohm’s Law

By |2025-02-12T09:25:59+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment: Ohm’s Law

  • It gives the relationship between potential difference and current through a wire in a circuit
  • According to the law:
  • \text{potential difference}\propto\text{current}
  • The current passing through a wire is proportional to the potential difference across its ends
  • Provided the temperature remains constant
  • An equation can thus be formed:
  • constant\dfrac{\text{potential difference(V)}}{\text{current […]
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The Ampere-Hour

By |2025-02-12T09:41:23+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: The Ampere-Hour

  • It is used to measure the current capacity of cells and batteries
  • is the amount of energy charge in a battery/cell that will allow one ampere of current to flow for one hour
  • It is thus a unit of measuring a cell/battery’s charge
  • For example if a battery is rated as […]
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Experiment: Demonstrating the effects of short-circuits and overloads

By |2025-02-12T09:06:51+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Demonstrating how fuses work Demonstrating how fuses work ZIMSEC O Level Combined Science Notes: Experiment: Demonstrating the effects of short-circuits and overloads

Aim: To demonstrate the effect of a short circuit/overloading of a circuit on a fuse

Materials: 6 or 12 V battery, copper wires, fuse wire/steel wool strand, switch, car headlamp, torch bulb, switch, […]

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