February 2025
Generators have many uses.Image credit wheelerdealers.co.zw ZIMSEC O Level Combined Science Notes: Uses of generators Transmission of electricity
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 […]
Science:Lighting
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 […]
Lightning and safety
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 […]
Current electricity
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
[…]
Potential difference
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
[…]
Experiment: Finding the resistance of a resistor using a voltmeter
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
- Set up the circuit as shown above
- Close the switch
- Read and record values of the […]
Resistors in parallel and in series
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 […]
Electrical Power
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 […]