physics-electricity

• a circuit with a single loop is a series circuit
• you can turn the lamp on and off using a switch. an open switch is break in the circuit
• in a series circuit you cannot turn the lamps on and off separately, the lamps are either all one or all off
• if one of the lamps in a series circuit breaks or blows, all the other lamps go out too
• you can use an ammeter to measure the current in a circuit. the current is the same everywhere in a series circuit
• in a parallel circuit there is more than one loop, the cell or battery pushes the current around each loop. these loops are called branches
• parallel circuits are sometimes called branching circuits
• if one lamp breaks or blows in a parallel circuit, all the other lamps will still work. The switch in each branch controls the lamps in that branch
• each lamp in a parallel circuit can be turned on and off independently
• as you add more branches in a parallel circuit , the current in each branch stays the same, the total current increases.
• you could increase the current in each branch and the total current by adding more cells
• the current splits when it gets to a junction of two or more branches
• in series circuits, if any part is broken then no electricity flows through the whole circuit
• series circuits have only one pathway for the current to flow around the circuit
• the current near the battery is equal to the sum of the currents in all the branches
• in a circuit, the force needed to make the charges move is provided by the battery. the size of the force depends on the voltage
• each component such a lamp provides a resistance to the flow of the charge
• if you add more lamps, less charge flows per second because more lamps provide more resistance to the flow of charge
• the buzzer provides more resistance to the flow of charge than a lamp
• the speed of the charge depends on the voltage and the resistance
• resistance is how difficult it is for current to flow through a component in a circuit
• current = voltage / resistance
• ohms is the unit for resistance
• resistance= voltage/current
• voltage=resistance x current
• there are two types of resistors: fixed resistors and variable resistors
• fixed resistor - has a fixed value of resistance, cannot be changed once set up
• variable resistors: the resistance of the resistor changes ,as the resistance increases , the lamp will get dimmer
• when you are choosing ideas to test , you need to make sure that they can be tested by collecting data
• a bright lamp transfers more energy per second. it emits more light per second than a dim lamp
• the rate at which energy is transferred is called power . Power is measured in watts (W)
• 1 kW = 1000W
• power=energy transferred(J)/time taken (S)
• current is measured in amps (A)
• an electric current transfers from the mains supply to the lamp
• the lamp in the lighthouse is much brighter than the lamps used in torches or in houses.
• the lamp in a torch transfers energy more slowly than the lighthouse lamp so the power is much less.
• mains supply: electricity generated in power stations and available through power sockets in buildings
• filament: the very thin, coiled piece of wire that glows inside a light bulb
• compact fluorescent lamps(CFLs) are energy saving lamps first sold in 1981.