4. Induced charge permanent – OPPOSITE as rod. 1. Charged rod is close – not touching. 2. Charge separation in object - GROUNDING 3. Electrons repelled towards Earth. e-e- Negative charge (excess e - ) Positive charge (lost e - ) INDUCTIONINDUCTION – with (-) rod

4. Induced charge permanent – OPPOSITE as rod. 1. Charged rod is close – not touching. 2. Charge separation in object - GROUNDING 3. Electrons attracted from Earth. e-e- Positive charge (lost e - ) Negative charge (gained e - ) INDUCTIONINDUCTION – with (+) rod

Define electric current Understand the movement of e - in a cell. Define coulomb, current, voltage, volt Understand schematic diagrams

KEY WORDS Electric currentConducting loop CircuitElectrodesAmmeter CoulombDry cellWet cell AmpereSchematic Load VoltVoltmeterVoltage Electric potential

Electric current is the movement of electrons (electric charge) through a conductor. The path of the traveling e - - called a conducting loop. Malleability, ductility, conducting Conductor– metal wire (copper or aluminum) – liquid electrolyte (salt water or acid) Flow of electrons from place to place through a conducting loop is called a circuit

An electric cell is used to produce a large, constant amount of electric charge. Wet cell : (Voltaic) Two different metals – electrodes - in a liquid conductor. One metal is called the positive electrode. The other is the negative electrode.

Ammeter: Tool to measure the electric current in a circuit. Electrons move from the (-) electrode (repelled) through the conducting loop to the (+) electrode (attracted). Chemical reactions in the cell constantly produce free electrons – accumulate on negative electrode.

Dry cell: Electrolyte is a thick paste (acid or salt). Makes for easy handling – batteries. Rod: + electrode (cathode) Casing: - electrode (anode) electrolyte paste

Electric circuits are drawn using symbols – schematic diagrams. switch ●● conductor cells (battery) load + - A electrical load is anything that converts electric charge into work – toaster, light, hairdryer…

●● + - ●● + - e-e- e-e- Closed circuit (on) Open circuit (off) Circuits can either be opened or closed by a switch.

Current – I Ammeters only record the huge number of electrons passing through the conductor – current. 1 coulomb equals 6.25 billion billion (6.25 x ) electrons. Units are Ampere (A) 1 coulomb per 1 second = 1 A

Electric current and hazards 0.8A – charge needed to light a 100W bulb 0.2 A – severe burns, heart stops, lungs stop. (“let go” threshold) 0.02 A – breathing affected, muscles contract A – muscles tingle.

Voltage – V It takes energy (work) to free electrons by the chemical reaction of a cell – energy is stored in each electron. Energy contained in an electron is called the electric potential. Voltage is the difference between the el. potential at the negative and positive electrodes. As e - move through a circuit they lose all potential energy.

Voltage 550 V – potential energy of a Power station. 120 V – potential energy of home wall outlet. 9 V – smoke alarm battery 1.6 V– AA battery Units are volts (V) – measured by a voltmeter Energy per 1 coulomb of e - = 1 V

+ electrode - electrode electrolyte paste 5.5 Volt battery 5.5 Volts 0 Volts Voltage Volts (el. pot. difference) Pot. energy in an e Volts

Metals or electrolytes allow electrons to flow. Electric current is the movement of electrons in a circuit. Cells have positive and negative electrodes. Electrons build up on the negative electrode. Current is the amount of e - moving – coulomb Current is measured in Amperes. Voltage is the difference between the potential energy of electrons at two point in a circuit. Voltage is measured in Volts. Circuits can been drawn in symbols – schematic.