Circuits and Circuit Elements Schematic Diagrams and Circuits

Schematic Diagrams and Circuits Schematic diagram – a representation of a circuit that uses lines to represent wire and different symbols to represent components Also called circuit diagrams

Electric Circuits

Electric Circuits Electric circuit – a set of electrical components connected uch that they provide one or more complete paths for the movement of charges Load – any element or group of elements that dissipate energy Needs a source of potential difference and electrical energy (battery) and a load (bulb) Circuits can be either open or closed Closed circuit – has a pathway through the circuit from one positive terminal of the battery to the negative Open circuit – does not have such a pathway

Electric Circuits Short circuits Leads to overload Occurs when a circuit does not have a load (no resistance) Wires cannot hold that much current, and their insulation may melt or catch on fire Grounding is used to prevent electric shock from short circuits

Electric Circuits Circuit breaker – a device that protects a circuit from current overloads Trip when the current overloads Acts like a switch

Electric Circuits The source of potential difference and electrical energy is the circuit’s emf or electromotive force Emf - Energy per unit charge supplied by a source of electric current Batteries and generators Terminal voltage is less than the emf Battery acts as both an emf and a resistor, although we will ignore internal resistance of the battery

Electric Circuits Emf is not a true force Potential difference Voltage rating on a battery (1.5 V) Terminal Voltage = emf – current * resistance ΔV = ε - IR

Electric Circuits Potential difference across a load equals terminal voltage As charges move from one terminal to the other, the chemical energy of the battery is converted into the electrical potential energy of the charges As charges move through a circuit, their electrical potential energy is converted to other forms of energy (kinetic, thermal, light) Energy in a circuit must be conserved, so the energy gained in the battery must be equal to the energy lost in the load Therefore, the potential increase across the battery must equal the potential decrease of the load