Electricity

3 SPM Form 5 Physics Mind Map Formulae List – Chapter 2

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Click on the image to enlarge.

The images above shows the formulae that students need to know in Malaysia SPM Physics syllabus in Mind Map form. You may click on the image to enlarge it for a better view. You may also download and print it out for further reference.

Electricity is the second chapter in SPM Form 5 Physics. There are a lot of formulae in this chapter, and most of them look similar. In order to answer the calculation questions, you must understand how the potential difference and current change in a circuit.

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3 Series Circuit and Parallel Circuit

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Series Circuit and Parallel Circuit

  1. The resistors connected in one non-branched wire is said to be connected in series, whereas resistors connected in a branched wire is said to be connected in parallel.
  2. In the diagram above, (a), (b) and (c) are series circuit whereas (d), (e) (f) and (g) are parallel circuit.

3.1 Electric Field

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Electric Field


  1. An electric field is a region in which an electric charged particle experiences an electric force.
  2. Electric field is represented by a number of lines with arrows, called electric lines of force or electric field lines.
  3. The direction of the field at a point is defined by the direction of the electric force exerted on a positive test charge placed at that point.
  4. The strength of the electric field is indicated by how close the field lines are to each other. The closer the field lines, the stronger the electric field in that region.
    Example
  5. The lines of force are directed outwards for a positive charge and inwards for a negative charge.
  6. The electric line of force will never cross each other.
  7. The figure shows a few examples of the field pattern that you need to know in the SPM syllabus.

Effect of Electric Field on a Ping Pong Ball Coated with Conducting Material


  1. A ping ball coated with conducting material is hung by a nylon thread.
  2. When the ping pong ball is placed in between 2 plates connected to a Extra High Tension (E.H.T.) power supply, opposite charges are induced on the surface of the ball. The ball will still remain stationary. This is because the force exert on the ball by the positive plate is equal to the force exerted on it by the negative plate.
  3. If the ping pong ball is displaced to the right to touch the positive plate, it will then be charged with positive charge. Since like charges repel, the ball will be pushed towards the negative plate.
  4. When the ping pong ball touches the negative plate, it will be charged with negative charge. Again, like charge repel, the ball will be pushed towards the positive plate. This process repeats again and again, causes the ping pong ball oscillates to and fro continuously between the two plates.

A Candle Flame in an Electric Field


  1. Normally, with absent of wind, the flame of a candle is symmetry.
  2. The heat of the candle flame removes electrons from the air molecules around it, and therefore ionised the molecule. As a result, the flame is surrounded by a large number of positive and negative ions.
  3. If the candle is placed in between 2 plates connected to a Extra High Tension (E.H.T.) power supply, the positive ions will be attracted to the negative plate while the negative ions will be attracted to the positive plate.
  4. The spreading of the flame is not symmetry. This is because the positive ions are much bigger than the negative ions; it will collide with the other air molecule and bring more air molecule towards the negative plate.

3 Electric Charge

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Electric Charge

  1. There are two kinds of electric charge, namely the positive charge and the negative charge.
  2. Like charge repel each other.
  3. Unlike charge attract each other.
  4. A neutral body can be attracted by another body which has either a positive or negative charge.
  5. The SI unit of electric charge is Coulomb (C).
    Example
    Charge of 1 electron = -1.6 x 10-19C
    Charge of 1 proton = +1.6 x 10-19C
  6. A Van de Graaff generator can be used to generate charges.
  7. Materials that allow electrons to pass through them are conductors.
  8. Charged conductors become neutral when they are earthed.

Charge and Relative Charge

Sum of Charge

Sum of charge
= number of charge particles × charge of 1 particle

Q=ne

Example:
Find the charge of 2.5 x 1019 electrons.
(Charge of 1 electron is   -1.6 x 10-19C)

Answer:
Number of electrons, n = 2.5 x 1019
Charge of 1 electron, e = -1.6 x 10-19C
Q=ne
Q=(2.5× 1019 )(−1.6× 10−19 )
Q=−4C

3 SPM Form 5 Physics Chapter 2 – Electricity

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  1. Fundamental of Electricity
    1. Electric Charge
    2. Electric Field
    3. Effect of Electric Field
      1. Effect of Electric Field on a Ping Pong Ball Coated with Conducting Material
      2. A Candle Flame in an Electric Field
    4. Current
    5. Potential and Potential Difference
      1. Relationship Between Current and Potential Difference
      2. Resistance
  2. Series Circuit and Parallel Circuit
    1. Resistance in series and parallel Circuit
      1. Comparing the resistance in series/parallel/combine circuit
      2. Finding the resistance of an individual resistor
    2. Current in a Circiut
    3. Potential and Potential Difference in a Circuit
    4. Finding Current in a Series Circuit
    5. Finding Current in a Parallel Circuit
    6. Finding Potential Difference in a Series Circuit
  3. Electromotive Force
    1. Difference between Electromotive Force and Potential Difference
    2. Internal Resistance and Potential Difference Drop
    3. Measuring e.m.f. and Internal Resistance
      1. Open Circuit/Close Circuit
      2. Simultaneous Equation
      3. Linear Graph
  4. Electrical Energy, Power and Efficiency
    1. Electrical Energy
    2. Electrical Power
      1. Sum of the Power
      2. Power Rating
      3. Energy Consumption
    3. Efficiency of Electrical Appliance
    4. Steps to Save Electricity

Objective Questions

  1. Electric Charge and Field (6 Questions)
  2. Current (7 Questions)
  3. Potential Difference (5 Questions)
  4. Ohm’s Law and Resistivity (7 Questions)
  5. Understanding Circuit – Resistance (7 Questions)
  6. Circuit – Current (4 Questions)
  7. Circuit – Potential Difference (6 Questions)
  8. Electromotive Force (7 Questions)
  9. Electrical Energy and Power (7 Questions)