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Physics Form 4: Chapter 5 - Concave Lens Ray Diagrams

Concave lens is a diverging lens. The image form is smaller than the object, virtual and upright. Concave lens always produce images that share these characteristics. The location of the object does not affect the characteristic of the image.

Chemistry Form 4: Chapter 2 - Structure of an Atom

   

• Atom consists of electrons surrounding a nucleus that contains protons and neutrons.
• Electrons are arranged around the nucleus in energy levels or shells. 
• The mass of an atom is concentrated in nucleus which contained the protons and neutrons.
• The nucleus is positively charged because of the presence of protons which are positively charged and the neutrons are neutral.
• The atom is neutral because the number of protons and the number of electrons are equal

Subatomic particles	Symbol	Relative mass	Relative   charged	Position
Proton	P	1	+1	Nucleus
Neutron	N	1	0
Electron	e-	1/1837 » 0	-1	Orbit

Symbol of Element

Physics Form 4: Chapter 1 - Vernier Calipers

A vernier caliper can measure to the nearest 0.1 mm or 0.01 cm. The ten divisions of the vernier scale on the vernier caliper are spaced over 0.9 cm of the main scale and the aim is to select the vernier graduation which is nearest to being in line with a main scale graduation. 

• The inner jaws is used to measure inner diameter of the object.
• The outer jaws is used to measure outer diameter of the object.

How to read a vernier caliper:

Reading = main scale + vernier scale

How about this one?

Reading = 1.2 + 0.03

                 = 1.23 cm

Click on the diagram below to play!

Chemistry Form 5: Chapter 5 - Making of Soap

Soaps are sodium or potassium salts of fatty acids. Soaps are prepared by hydrolyzing fats or oils under alkaline condition. This reaction is called saponification.

·         The fats or oils are hydrolysed first to form glycerol and fatty acids. The acids then react with an alkali to form the corresponding sodium or potassium salts.

·         The soap formed can be precipitated by adding sodium chloride. This is because sodium chloride lowers the solubility of soap in water.

·         The glycerol and excess sodium hydroxide solution are removed by rinsing the soap formed with water.

·         Soaps feel slippery and form lather when they are shaken with water.

Physics Form 4: Chapter 3 - Application of Bernoulli principle (WindSurfing)

 

• The air flow over the sail causes an increase in pressure on the windward side and a decrease on the leeward side
• Area of leeward side has a low pressure because of the high speed of the wind.
• A resultant force acts in the direction of F.
• This resultant force can be resolved into component to the right and left.
• The component to the right can be balanced by the surfer who pulls it to the left.
• Therefore, there exists a resultant force to the front so that the surfer moves to the front.
• Factors affect the resultant force is the strength of the wind and the shape of the sail. 

Mirror of Georgetown Heritage City

A cutting edge street art project by international artist Ernest Zacharevic, the project consists of six to 12 mural paintings created on the walls of buildings within the Georgetown heritage area. The paintings will depict figure drawings and portraits of various inhabitants of the city celebrating the multiculturalism and diversity of the town.

All photos above are courtesy of Ernest Zacharevic and Penang traveltips site

Ernest Zacharevic facebook page

 Penang Traveltips site