2013/03/15



1. Write down the TWO conditions needed for electricity to flow.
    - The circuit must a closed circuit. 
    - There need a source of electrical energy. 

2. A circuit that is complete is called closed circuit.
    It there is a gap in a circuit, the circuit is called open circuit.

3. The materials that do not allow electricity to pass through are called insulator.
    The materials that allow electricity to pass through are called conductor.

4. Determine if the following things can allow electricity to pass through.
    ü --> Iron paper clip, Aluminium foil, Coin, Tap water, Graphite
    û --> Wooden chopsticks, Glass rod, Rubber tubing, Cola, Oil



5. State the function of a switch.
    To control the flow of free electron. 

6. When a switch is closed, the metal parts are connected with each other and the circuit becomes closed. Therefore, free electrons can pass through the circuit.

7. An atom consists of a positively charged nucleus surrounded by many tiny negatively charged electrons.

8.  The electric current in a metal wire is a flow of free electrons from the negative pole of the cell to the positive pole of the cell.

9. In a circuit,  Dry cell provides energy for the free electrons.
                       Connecting wire provides a path for the free electrons to flow through.
                       Bulb take the energy carried by the free electrons.
                       Switch can control the flow of free electron.

10. In the electric circuit, the electrical energy carried by free electrons is changed into light energy and heat energy in the bulb.

11. Electric current can be measured by ammeter.
      Electric current is measured in ampere (A).
      Small currents are measured in milliampere (mA).

12. 1 mA = 1/1000 A

13. When the electric current passing through a light bulb increases, the light bulb becomes brighter.

14. Voltage is the 'electrical push' that make electrons flow in a circuit. The higher the voltage, the larger is the electrical push.

15. Voltage can be measured by voltmeter.
      Voltage is measured in volt (V).

16. When the voltage in a circuit is higher, the current in the circuit will be larger.

17. The amount of voltage in a circuit depends on the dry cell used in the circuit.

18. When the number of light bulbs connected in a circuit increases, the voltage of the batteries remain unchanged.

19. Voltage in a circuit is higher if the cells are connected in the same direction.


20. 

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