Post on 01-Jan-2016
9.1: Conductors, Insulators and Electric Current:
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.
9.3: Electric Current:
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.
9.5: Voltage (Potential difference): 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.
9.6: Electric Circuit: A circuit have power supply
(cell/battery), switch, any device and connecting wires.
Switch closed = ON, switch open = OFF
9.8: Series Circuit: A circuit with single loop where
current can flow in only one path is called series circuit.
The following picture shows the series circuit:
9.8.1: Advantages and Disadvantages of 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.
9.9: Parallel Circuit: 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:
9.9.1: Advantages and Disadvantages of Parallel 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.