-Shakil Raiman

 Conductor  Insulator  Current  Measuring Current  Voltage  Measuring Voltage

 An electric current is a flow of charge  Electrons carry the charge  Metals are good conductors as more free electrons are present and electrons can move easily.  Electrons cannot move easily in insulators.

 Some electron in a metal will flow when a voltage is applied.

 The rate of flow of charge is called an electric current.  Current = Charge / Time  I = Q/t  Unit: Ampere (A)  It is measured by Ammeter.  Ammeter has very low resistance.  It is connected in series in a circuit.

 Charge = Current × time  Unit: Coulomb (C)

 Voltage is work done per unit charge to transfer the charge across any point in a circuit.  Unit: Volt (V)  It is measured by Voltmeter  Voltmeter has high resistance  It is connected in parallel to a device.

 A circuit have power supply (cell/battery), switch, any device and connecting wires.  Switch closed = ON, switch open = OFF

 A circuit with single loop where current can flow in only one path is called series circuit.  The following picture shows the series circuit:

 Advantages:  Less wire is needed.  Single switch can operate all devices.  Disadvantages:  If one bulb breaks all other bulb will go off.  As voltage is shared more the bulb added more the dimmer they all become.  Examples:  Decorative lights.

 A circuit with multiple loop where current can flow in more than one path is called parallel circuit.  The following picture shows the series circuit:

 Advantages:  Each device can be operated individually.  If one bulb breaks other works normally.  All device can work with full power or all bulb can work with full brightness.  Disadvantages:  More wire is needed.  Example:  Household connections.

 THANK YOU ALL