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A-Level Mathematics Tuition Singapore/JC Maths/H2 Math Tuition and Tutor

Hi A-Level/H2 Math Students

J1 – Practice Exam questions on Functions and Graphing Technique

J2 – Teaching Normal Distributions

From A Level Math Tutors

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O-Level Singapore/O-Level/Physics and Chemistry Tuition/Physics Tutor

Electrostatic – Key Concepts II

Some hazards of electrostatics

1. Lightning

Thunderclouds are charged by friction between the water molecules in the thunderclouds and air molecules.

It then ionises the air and the ionised air provides a conducting path for electric charge to be discharged to the nearest or sharpest object on the ground.

2. Electrostatic discharge

Excessive charges may build up due to friction. Sudden discharge may cause sparks and ignite flammable materials nearby

Electronic equipment, such as computer boards and hard drive, can be easily damaged.

Such equipments are usually packed in antistatic packaging materials.

See movie : Static @ Petrol.

Practical applications of electrostatics

1. Laser printer

2. Electrostatic precipitator

3. Spray painting

As the spray leaves the nozzle, the particles of paint become charged by friction.

The paint particles contain like charges thus they spread out when they are sprayed on a car body.

The charged paint particles will be attracted to the metallic car body.

From O level Physics Tutor

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O-Level Singapore/O-Level/Pure Physics Tuition/Physics Tutor

Electrostatic – Key Concepts II

Some hazards of electrostatics

1. Lightning

Thunderclouds are charged by friction between the water molecules in the thunderclouds and air molecules.

It then ionises the air and the ionised air provides a conducting path for electric charge to be discharged to the nearest or sharpest object on the ground.

2. Electrostatic discharge

Excessive charges may build up due to friction. Sudden discharge may cause sparks and ignite flammable materials nearby

Electronic equipment, such as computer boards and hard drive, can be easily damaged.

Such equipments are usually packed in antistatic packaging materials.

See movie : Static @ Petrol.

Practical applications of electrostatics

1. Laser printer

2. Electrostatic precipitator

3. Spray painting

As the spray leaves the nozzle, the particles of paint become charged by friction.

The paint particles contain like charges thus they spread out when they are sprayed on a car body.

The charged paint particles will be attracted to the metallic car body.

From O level Physics Tutor

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O Level E Maths Tuition Singapore/Tuition O Level E Maths/Tutor

Simple Probability

Definition
If an event A can happen in m ways of n equality likely ways, then the probability or chance of n happening denoted by P(A) is defined as
P(A) = m/n

Probability that event A occurs
=(number of outcomes favorable to the event of A)/(Total number of equality possible outcomes)

Properties of Probability
1. If A is an impossible event, then P(A)=0
2. If A is a sure event, then P(A)=1
3. if A is any events
P(A)smaller or equal to 1
P(A)greater or equal to 0

From O-Level Elementary Mathematics Singapore Tutor

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O-Level Additional Mathematics Tuition Singapore

S3 – Teaching Linear law

S4 – Teaching Application of Integration Part 3

O-Level Additional Mathematics Tutor

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O Level Chemistry Tuition Singapore/Chemistry O Level Tuition/Tutor

Chapter 17 – Speed of Reaction

1. Different chemical reactions take place at different speeds

2. Speed of reaction = change in amount of reactant or product/Time taken

3. Speed of reaction = change in volume gas/Time taken

4. For reactions involving solutions, an increase in the concentration of a reactant increases the speed of reaction.

5. For reactions involving gases, an increase in the pressure of a gas increases the speed of reaction.

5. Reactions take place faster when the solid is broken into smaller pieces.

6. The higher the temperature, the faster the movement of the particles and the greater the number of collisions. Hence, reactions take place faster when the temperature is increased.

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A-Level Chemistry Tuition Singapore/H2 Chemistry Tuition/JC Chemistry Tutor

Chemical Bonding FAQ 3

Do you know?

The fact that ice is less dense than water causes water to freeze downwards. This helps living organisms in a body of water to survive freezing conditions!

As the temperature of water near the surface drops, the density of water increases. Cold water sinks while warmer water, which is less dense, rises. This convection motion of water continues until the temperature of the water reaches 4 °C. Below this temperature, the density of water
decreases with decreasing temperature so that water colder than 4 °C no longer sinks. On further cooling, the water begins to freeze at the surface. The ice layer formed does not sink as it is less dense than water.

This layer of ice helps to insulate the water underneath from further heat loss, thus keeping the water below it from freezing solid. Hence, living things can survive in ponds and rivers even when the temperature falls below freezing.

Question 1: Explain why the boiling point of propane, dimethyl ether and ethanol deviates so greatly even though their electron cloud sizes are similar.

Since the electron cloud sizes of the three compounds are similar, the magnitudes of instantaneous dipole–induced dipole (id–id) interactions in the three compounds are similar.

Propane is non–polar so that the intermolecular forces between propane molecules are due only to id–id interactions.

Dimethyl ether is polar so that besides id–id interactions, permanent dipole–permanent dipole (pd–pd) interactions also exist between the molecules. Since boiling involves breaking intermolecular forces, more energy is required to overcome the stronger pd–pd interactions between dimethyl ether molecules compared to the weaker id–id interactions between propane molecules. Hence the boiling point of dimethyl ether is significantly higher than propane.

Ethanol contains a hydrogen atom covalently bonded to the small and highly
electronegative O atom so that hydrogen bonding exists between ethanol molecules. Since ethanol contains hydrogen bonding besides pd–pd interactions and id–id interactions, intermolecular forces between ethanol molecules are the strongest,hence the energy required to overcome intermolecular interactions in ethanol is greater than in propane and dimethylether. Hence ethanol has a much greater boiling point than both propane and dimethylether.

Question 2: Explain why iodine has a higher boiling point than water even though iodine has only instantaneous dipole–induced dipole interactions and water can form hydrogen bonds.

The strength of instantaneous dipole–induced dipole interactions depends on the size of the electron cloud. Iodine has a much larger electron cloud than water so that the instantaneous dipole–induced dipole interactions between iodine molecules are significantly stronger than the hydrogen bonding between water molecules which have much smaller number of electrons.

Since boiling involves overcoming the intermolecular attractions between molecules, a greater amount of energy is required to overcome the id−id forces between iodine molecules compared to the id−id forces and the hydrogen bonds between water molecules.

FAQ: Explain why ionic compounds do not dissolve in non-polar solvents.

Answer: The ion−solvent interaction is much too weak to overcome the
strong electrostatic attraction between the ions in the crystal lattice.

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A-Level Mathematics Tuition Singapore/JC Maths/H2 Math Tuition and Tutor

Hi A-Level/H2 Math Students

J1 – Practice Exam questions on AP & GP and Series and Sequences

J2 – Teaching Poisson Distributions and continue practice exam questions on Permutations and Combinations.

From A Level Math Tutors

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A Level GP/General Paper Tuition Singapore

The Topic Sentence

A topic sentence serves to introduce the topic by stating the subject of the paragraph and the attitude about the topic. Generally, because the topic sentence does introduce the controlling idea of the paragraph, it is a good idea to place it at or near the beginning of the paragraph.

Checklist for a good topic sentence:

• Does it summarise the single main point of your paragraph?
• Does it have a logical and direct relation to the thesis for your essay?
• Does it contain the appropriate connectors / language structures that explicitly tells the reader the link between the current paragraph and the preceding paragraphs?
• Does it have a clear focus on a particular aspect of your topic?
Substantiation

This material is used to support the opinion or attitude expressed in your topic statement. Ask yourself – what must I do to convince the reader that my claim is reasonable / valid / acceptable? Does it back up, clarify, illustrate, explain or prove the point you make in your topic sentence?

Please contact 9863 9633 fir examples on Topic Sentence

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A-Level Physics Tuition Singapore/H2 Physics Tuition/JC Physics Tutor

Hi All A-Level/JC/H2/H1 Physics Students

Exam based questions – Quantum Physics

5. Describe and interpret qualitatively the evidence provided by electron diffraction for the wave nature of particles.

When a beam of electrons passed through a thin film of crystal (e.g. graphite),the dispersion pattern of the emergent electrons produced on a screen (coated fluorescent)is observed to be similar to the diffraction pattern produced by a beam of X-ray.

This phenomenon provides evidence for the wave nature of particles like electrons.

6. Explain how spectral lines show discrete energy levels in an atom.
An emission spectrum consists of a set of discrete wavelengths.

A photon is emitted from an isolated atom when one of its electrons transits from a higher to a lower energy level.
Energy of the photon is equal to the energy difference between the two levels involved in the transition.

7. Distinguish between emission and absorption line spectra.

An emission line spectrum of an element consists of colored lines on dark background while an absorption spectrum consists of dark lines on colored background, at the same discrete wavelength positions for the same element.

For emission spectra, electrons transit from higher energy level to lower energy level.For absorption spectra, electrons transit from lower energy level to higher energy level.

9. Explain the origins of the features of a typical X – ray spectrum using quantum theory.

It is produced in an X-ray tube, where fast electrons strike a metallic target (e.g. tungsten).

Two distinct features of an X-ray spectrum:
Spikes (Ka and Kb)

– due to characteristic radiation of the target metal in which electrons transit from very high to low energy level.

For more exam based questions, please contact Mr Ong @9863 9633

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A-Level Economics Tuition Singapore/H2/H1 Economics Tuition

Hi J2 H1/H2 Economics Tuition Students

Reading Materials for Inflation

SHOE-LEATHER COST of Inflation

One real cost is when individuals spend time and other resources fighting the effects of inflation. This creates a dead weight loss since now real variables are being diverted from a productive use to reducing the effects of inflation. Shoe leather cost refers to the cost associated with the time and efforts (more specifically the opportunity cost of time and energy) that people spend trying to counter-act the negative effects of inflation (Figure 0). For instance, in periods of inflation, if an individual holds cash in hand they will be subject to the inflation tax. To help reduce the effect of the inflation tax on their money holdings an individual might decide to deposit more of their cash into an interest bearing account at their bank. The term “shoe leather cost” comes from the fact that more walking is required (historically, although the rise of the Internet has reduced it) to go to the bank and get cash and spend it, thus wearing out shoes more quickly, and consequently spending more money on shoes. The actual cost of reducing money holdings is the additional time and convenience that must be sacrificed to keep less money on hand than would be required if there were no inflation.

As an example, Bolivia experienced its worst inflation between 1984 and 1986. Before 1984, the highest denomination was 1,000 pesos bolivianos. By 1985, the highest denomination was 10 million pesos bolivianos. In 1985, a Bolivian note for 1 million pesos was worth 55 cents in U.S. dollars, one-thousandth of its exchange value of $5,000 less than three years previously. In the 1987 currency reform, the peso boliviano was replaced by the boliviano at a rate of 1,000,000:1.

The Bolivian government was so far in debt that it was no longer credit worthy to sell bonds internationally or domestically. They began to sell bonds directly to the Bolivian central bank to pay public workers. These injections of un-backed pesos into the market drove down the value of pesos and increased the price of food and other goods and led to hyperinflation. The hyperinflation in Bolivia reached its peak in July 1985 when the value of U.S. $1 equaled two million pesos, the inflation had increased by 3,000% in only a year.

The hyperinflation was only made worse by the sale of U.S. dollars on the black market. An example of shoe leather costs from this time is when Bolivians spend time and energy trying to convert their pesos bolivianos into a more stable currency, the U.S. dollar. They were diverting resource away from a productive use that would create value in the economy. The value of those diverted resources is a real cost of inflation.

From A Level Tutor

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A-Level Economics Tuition Singapore/H2/H1 Economics Tuition

Hi J1 H1/H2 Economics Tuition Students

Microeconomics Tutorial 4 – Case Study

Question 1 Demand and supply imbalances in the UK energy market
In the 1990s the UK government took a number of steps to privatise the market for energy. Natural gas and electricity are the most popular domestic fuels in the UK and the markets for both were deregulated to allow greater competition. The aim was to give customers lower prices and greater choice between suppliers. Two organizations were created to ensure benefits for the consumer. The Office of Gas and Electricity (Ofgem)
was given responsibility for ensuring that the markets were competitive. Energy watch was established in November 2000 to represent the interests of consumers. Consumers now purchase their gas and electricity from a small number of private sector suppliers.

Extract 1 : Gas warning : not enough to meet demand

A warning was issued yesterday that the UK was in danger of not having enough natural gas to meet demand. The warning sent prices spiraling up fourfold. The UK gas market has been caught out because the country’s only significant gas storage facility is out of action because of a fire. Centrica, the company that runs the facility, said that it could not
be sure when it would get the supply facility back into action. Despite this problem, which could lead to some manufacturing companies having their supplies cut off, there has been little increased supply from outside the UK from countries such as the Netherlands where gas is still plentiful. In the UK the price of gas hit 250 pence per unit yesterday, which is three times more than in the Netherlands, but the gas pipeline
connecting the UK to suppliers in the Netherlands was only running half-full. Although some large industrial users might have to forgo supplies, residential consumers have been promised that no further residential price increases are planned at this time. British Gas, the company that supplies 53% of the residential gas market, increased prices by 12% in September 2004 and a further 36% by March 2006. Many gas users have switched to alternative fuels. Electricity prices have also been increased by 18.4%
by a leading supplier while most other suppliers have increased prices, but by smaller amounts.

UK politicians have criticized other governments in Europe for their slowness in deregulating energy markets. Yesterday the price of wholesale gas in the Netherlands was, as low as 70 pence per unit. A new pipeline carrying suppliers from Norway is expected to begin operations in October.

Source : Guardian Unlimited, 14 March 2006

For complete assignment, please contact 9863 9633 or 96790479

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O-Level Additional Mathematics Tuition Singapore

S3 – Teaching Coordinate Geometry

S4 – Teaching Application of Integration Part 2

O-Level Additional Mathematics Tutor

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O Level E Maths Tuition Singapore/Tuition O Level E Maths/Tutor

Investigative Problems & Number Patterns

Problem Solving

1. Reading and understanding the problem.

2. Choosing an appropriate strategy to solve the problem.

3. Apply the strategy.

4. Check the answer and looking back.

Some of the common strategies used in solving mathematics problems are:

1. Simplify the problem
2. Draw a diagram or table
3. pattern recognition
4. Trial and error
5. Use of algebra
6. Exhaustive listing
7. Use of models
8. Work backwards
9. Solve part of the problem
10. Eliminate the unlikely possibilities

From O-Level Elementary Mathematics Singapore Tutor

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O-Level Singapore/O-Level/Physics and Chemistry Tuition/Physics Tutor

Electrostatic – Hazards and Applications of Electrostatics

1. An electric field is a region where an electric charge experiences an electric force.

2. The direction of the field is the direction of the force on a small positive charge.

3. Some hazards of electrostatic charging are lightning and electrostatic discharge.

4. Some uses of electrostatic charging are the laser printer, photocopier and electrostatic precipitators.

From O level Physics Tutor

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