Model of a cell

A cell contains several structures, including:

1. Nucleus - The cell's control centre, containing DNA and regulating cell activity.

2. Endoplasmic reticulum (ER) - A network of membranes involved in protein synthesis and lipid metabolism.

3. Golgi apparatus - A stack of flattened membranes that modify, sort, and package proteins and lipids for transport to other parts or outside the cell.

4. Mitochondria - The cell's powerhouse, responsible for producing energy through cellular respiration.

5. Lysosomes - Small, spherical structures that contain digestive enzymes and break down waste and cellular debris.

6. Vacuoles - Large, fluid-filled organelles that store materials such as water, salts, and pigments.

7. Microfilaments and Microtubules - Tiny protein fibres that help maintain cell shape and support the cellular movement.

8. Peroxisomes - Small organelles containing enzymes involved in metabolic processes, including the breakdown of fatty acids and detoxifying harmful substances.

 

Spinning a wire connected to a beam galvanometer

How can spinning a single wire like a skipping rope connected to a beam galvanometer show electricity being generated? Nothing happens when both wires are spun together, but electricity is made if one of the pairs spins. And where does this energy come from? Fooled the students for quite a while. When a wire is passed through a magnetic field, a voltage, also known as an electromotive force (EMF), is generated in the wire. According to Faraday's law of electromagnetic induction, a changing magnetic field will induce an electromotive force (EMF) in a conductor. The EMF causes a flow of electric charges, which is an electric current.

In other words, the magnetic field acts as the source of energy that drives the flow of charges in the wire. The magnitude of the induced current depends on the strength of the magnetic field, the speed at which the wire moves through the field, and the length of the wire inside the magnetic field.

A beam galvanometer is a direct current (DC) electrical meter used to measure electrical current. It consists of a coil of wire suspended between the poles of a magnet. When a current flows through the coil, it creates a magnetic field that interacts with the magnetic field of the permanent magnet, causing the coil to rotate. The rotation angle is proportional to the magnitude of the current being measured. This movement is typically displayed on a scale or read out using a pointer. The coil is often attached to a lightweight metal beam or needle to increase its sensitivity, hence "the beam galvanometer."

Eureka Can

Science should be taught as a series of problems to find solutions to. Giving the student everything takes the excitement out of science. Science is about students discovering how to do something with a bit of guidance. I give out lots of the wrong equipment and get the students to choose what is best.

Charles Law

 It was the first time I had done Charles Law using a dried capillary tube and a bead of conc Sulfuric Acid to determine the volume against the temperature. The experiment took 3 hours, but I now know how to make it faster to fit into an hour lesson. Jacques Charles made a major contribution to the study of gases. In 1787, he discovered that gases have a linear relationship between their volume and temperature, provided the pressure remains constant. This is known as Charles's Law, which states that the volume of a gas is directly proportional to its temperature.

Paraffin block puzzle

 I confused many of the students with the paraffin block puzzle. The bottom is dark, the top light. Turn is round anyway, and the bottom is still dark. It kept the students amused for quite a while whilst they tried to work out what I had done to it.

Wireless Geiger Counter

After many months of waiting for my @Pascoscientific Wireless Geiger Counter and stand to arrive, I particularly like the stand, being able to place sources at different distances and placing different thicknesses of different materials to absorb the radiation.
 

Diffraction of light

 Diffraction of light using a laser going through a single pinhole in a piece of Aluminium foil. I like introducing a topic by demonstrating an effect or, better still, letting the students do their own demo and then letting them come up with an explanation of what is happening