O Level – Physics

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  • #3341

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    Key Points – Turning Effect of Moment

    1. The moment of a force about a point is the product of the force F and the perpendicular distance d from the pivot to the line of action of the force

    Moment = F x d

    2. The SI unit ofr moment of a force is Newton meter – Nm

    3. moment of a force is a vector. The direction of the moment is either clockwise or anticlockwise about the pivot.

    4. There are two conditions for an object in equilibrium.

    a) Net force is zero ie F(net) = 0
    b) Net moment due to the external force is zero

    5. The principle of moments states that when an object is in equilibrium, the sum of the clockwise moments is equals the sum of the anticlockwise moments.

    6. The centre of gravity of an object is the point through which its entire weight appears to act.

    7. CG of regular-shape objects can be determined by geometrical symmetry.

    8. CG of irregular-shape objects can be determined by the plumbline experiments.

    9. The stability of an object increases when the base area increases or the CG is lowered.

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3356

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    Key Points – Energy, Work and Power

    1. Energy is the ability to do work.

    2. Energy can exist in many forms. It can be converted from one form to another.

    3. Gravitational potential energy Ep is the energy possessed by an object due to its position in a gravitational field.

    Ep = mgh
    m = mass of the object
    g = gravitational constant
    h = height of the object from a reference level

    4. Kinetics energy Ek is the energy possessed by an object due to its motion.

    Ek = 1/2mv^2
    m = mass of the object
    v = velocity of the object

    5. Principle of conservation of energy states that the total amount of energy in an isolated system is constant.

    Total initial energy = Total final energy

    6. Work done of an object WD is the product of force F acting on the object and distance d travelled by the object in the direction of the force.

    WD = F x d

    7. SI unit of energy and work done is Joule (J)

    8. Power P is the rate of work done WD

    P = WD/Time

    9. Power is also define as rate of energy E

    P = E/Time

    10. SI unit for power is watt (w)

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3392

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    Key Points – Pressure

    1. Pressure P is the force F acting on a surface divided by the area A of the surface.

    P = F/A
    P = Newton per meter square
    F = Newton
    A = meter square

    2. Pressure P at a certain depth h of a liquid with density p under the influence of gravitational field strength g is given by :

    P = pgh

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3407

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    Key Points – Temperature

    1. Temperature is a measure how hot or cold an object. It is an indication of the amount of heat energy of an object.

    2. SI unit of temperature is Kelvin (k). However degree Celsius oC is more commonly used.

    3. A thermonetric property is a physical property that changes according to the temperature.

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3408

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    Key Points – Temperature

    1. Temperature is a measure how hot or cold an object. It is an indication of the amount of heat energy of an object.

    2. SI unit of temperature is Kelvin (k). However degree Celsius oC is more commonly used.

    3. A thermonetric property is a physical property that changes according to the temperature.

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3451

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    Key Points – Transfer of Thermal Energy

    1. The transfer of thermal energy or heat always occurs from a region higher temperature to a region of lower temperature.

    2. When two objects in thermal contact are in thermal equilibrium, they have the same temperature.

    3. The three processes of thermal transfer are conduction, convection and radiations.

    4. Conduction involves the transfer of kinetic energy between neighboring particles in the medium due to collisions.

    5. Convection involves the movement of the fluid particles due to a change in the density of fluid.

    6. Radiation is the transfer of thermal energy by electromagnetic waves. it can occur even in the absence of medium.

    7. The rate of thermal energy transfer by radiation depends on the colour, texture, temperature and area of the surface.

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3495

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    Key Points – Light

    1. Light travels in a straight lines.

    2. The First Law of Reflection states that the incident ray, the reflected ray and the normal all lie in the same plane.

    3. The Second law of Reflection states that the angle of incidence i is equal to the angle of reflection r

    i = r

    4. Refraction is the bending of light rays when they pass from one transparent medium into another.

    5. sin i/sin r = constant which is know as reflective index

    6. Critical angle c
    Sin c =1/n (n= reflective index)

    7. Focal length is the distance between the optical centre C and the focal point F

    8. Ray diagram can be used to determine if the image is real or virtual, upright or inverted, and magnified or diminished.

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3535

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    Key Points – Waves

    1. Transverse waves travel in a direction perpendicular to the direction of vibration.

    2. Longitudinal waves travel in a direction parallel to the direction of vibration.

    3. Waves transfer energy transfer without transferring matter.

    4. All points on a wave that are in phase have the same displacement and direction of motion.

    5. A wave front is an imaginary line connecting all the points of a wave that are in the same phase.

    6. The wavelength of a wave is the distance between any two consecutive points that are in phase. The unit of wavelength is in meter (m)

    7. The amplitude A a wave is the maximum displacement from the rest position. The unit for the amplitude is meter (m)

    8. The period T of a wave is the amount of tie taken for the wave to complete one full cycle. The unit for period is second (s)

    9. The frequency f of a wave is the number of cycles completed per unit time. The unit of the frequency is Hertz (Hz)

    f = 1/T

    10. The speed v of a wave is the distance travelled by the wave per unit time.

    v = f X wavelength

    11. When water wave enter greater depth, the wavelength increases. The frequency f of the wave remains unchanged as it is determined by the source.

    12. The speed v of water wave increases when the water depth increases. The speed v decreases when the water depth decreases.

    13. Refraction of water waves occurs when water waves enter a different depth at an angle.

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3560

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    Key Points – Electromagnetic Waves

    1. Electromagnetic waves are transverse waves. They transfer energy from one place to another without the need for a material medium.

    2. The speed of the electromagnetic waves in vacuum is 3 x 10^8 m/s

    3. Electromagnetic waves can be reflected and refracted.

    4. Velocity of the wave = frequency x wave length

    5. Electromagnetic Spectrum
    Frequency in the ascending order
    Radio waves
    Microwaves
    Infrared radiation
    Visible light
    Ultraviolet rays
    X-rays
    Gramma rays

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3599

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    Uses of Electromagnetic Waves

    1. Radio Waves
    – Radio broadcasting
    – Transmitting television programmes
    – Telecommunication
    – Wireless networking

    2. Microwaves
    – Satellite communication
    – For cooking food
    – Remote sensing (radar)

    3. Infrared
    – Night vision binoculars
    – Thermal imaging
    – Remote controls
    – Motion detector (in security systems)

    4. Visible light
    – Optical fibers for data transmission
    – Endoscopy (visual inspection of internal organs)
    – Photography

    5. Ultraviolet rays
    – Sunbeds
    – Florescence effect

    6. X-rays
    – Radiography
    – Detecting cracks in pipes and buildings

    7. Gamma rays
    – Sterilisation of medical equipment
    – Radiotherapy

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3647

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    Key Points – Sound

    1. Sound is a longitudinal wave produced by a vibrating source in a medium. It comprises compression and rarefaction.

    2. Unlike electromagnetic waves, sound waves cannot travel through vacuum. They requires a medium to propagate.

    3. The speed of the sound depend on the type of medium it travels in. Sound travels faster in solids, followed by liquids and travels the slowest by in gases.

    4. The speed of sound is 330 m/s

    5. The speed of sound increases when the temperature of the air increases.

    6. The loudness of the sound increases as the amplitude increases.

    7. The pitch of the sound wave increases as the frequency increases.

    8. When sound is reflected after striking a hard surface, an echo is formed.

    For more key points and exam based questions with full worked solution, please contact Mr Ong @9863 9633

    #3678

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    2014 Secondary 4 Preparatory Course

    11-Nov Mon 9am to 10.30am 1.5 hrs Kinematics

    12-Nov Tue 9am to 10.30am 1.5 hrs Dynamics

    13-Nov Wed 9am to 10.30am 1.5 hrs Forces

    14-Nov Thu 9am to 10.30am 1.5 hrs Mass, Weight and Density

    15-Nov Fri 9am to 10.30am 1.5 hrs Turning Rffect of Forces

    18-Nov Mon 9am to 10.30am 1.5 hrs Energy, Work abd Power

    19-Nov Tue 9am to 10.30am 1.5 hrs Pressure

    20-Nov Wed 9am to 10.30am 1.5 hrs Light 1

    21-Nov Thu 9am to 10.30am 1.5 hrs Light 2

    22-Nov Fri 9am to 10.30am 1.5 hrs Waves

    If you need help in the above topics, please contact Angie @96790479 or Mr Ong @98639633

    #3718

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    Power Revision

    O Level Physics – 2 hrs Each Lesson

    1. Kinematics – 2 lessons
    2. Dynamics – 2 lessons
    3. Forces – 1 lesson
    4. Turning Effect of Forces – 1 lesson
    5. Work Done, Energy & Power – 1 lesson
    6. Thermal Physics – 2 lessons
    7. Light – 2 lessons
    8. Current Electricity/DC Circuits/Practical Electricity – 3 lessons

    If you need help in the above topics, please contact Angie @96790479 or Mr Ong @98639633

    #3736

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    Key Points – Static Electricity

    1. Protons and electrons have electric charge. A proton positively charged while and electron is negatively charged.

    2. SI unit of electric charge is the coulomb (C)

    3. The electric force is the attraction between unlike charges or the repulsion between like charges.

    4. In electrical conductors, there are electric charges (usually electrons) that can move freely within the object.

    5. Electrical Insulators are materials in which the electric charges cannot move freely.

    6. Electric charges is due to the transfer of electrons from one object to another.
    – solid insulators can be charged by rubbing.
    – solid conductors can be charged by induction.

    7. Discharging is the process of neutralising a charged object by removing excess charges.

    8. An electric field is a region in which an electric charge experience an electric force. The direction of the electric field line represents the direction of the force experiences by a small positive test charge within the electric field

    If you need help in the above topics, please contact Angie @96790479 or Mr Ong @98639633

    #3759

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    Key Points – Current Electricity Part 1

    1. Electric current I is the rate of flow of electric charge through a cross section of a conductor

    I = Q/t

    Q = amount of charge in coulomb (c)
    t = time in second (s)

    2. SI unit for electric current is Ampere (A)

    3. The direction of conventional current is from the positive end of a cell or battery to the negative end. The directional of conventional current is opposite to that of electron flow.

    4. Electromotive force (e.m.f.) e of an electrical energy source is defined as he work done W by the electrical energy source in moving a unit charge around a complete circuit.

    e = W/Q

    5. Potential difference (p.d.) V between two points in a circuit is defined as the work done W in moving a unit charge between these two points.

    V = W/Q

    6. SI unit for e.m.f. and p.d. is volt (V)

    If you need help in the above topics, please contact Angie @96790479 or Mr Ong @98639633

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