IGCSE双语物理课程1.electrical quantities --current IG2.2.pptx

Electrical quantitieswordsn. [电] 安培计； ammeter英?/‘?m?t?/words安培n. 毫安 n. [电子] 微安 [电] 串联；串联； amp英?/?mp/milliamp英?/ mili?mp/ microampseries英?/s??ri?z; /in series 量 quantitycurrent电流resistance电阻voltage 电压 电池组batterycell 电池 电路circuit 元件component/k?m?p??n?nt/ 电流表ammeter /??mi?t?(r)/ In physics, a physical quantity is any physical property that can be quantified. that is, can be measured using numbers. (quantified 被量化) mass, length, time,temperature, electric current, force, velocity, Quantities QuantitiesWhat are the quantities in the circuit?current resistancevoltagecurrentFor an electric current to flow, two things are needed:1.A complete circuit for it to flow around2.Something to push it around the circuit. battery/b?t(?)r?/ 电池 is two or more cells connected end-to-end. circuit diagramEach component has its own standard symbolIn the circuit symbol for a cell, the longer linerepresents the positive terminal.What is electric current?Current flows from the positive terminal of the supply, around the circuit, and back to the negative terminal.What is actually travelling around the circuit? A current is a flow of electric charge.Measuring electric currentTo measure electric current, we use ammeterAn analogue meter has a needle, which moves across a scale A digital meter gives a direct read-out in figures.Measuring electric currentTo measure electric current, we use ammeterIt is connected into a circuit in series. The reading on an ammeter is in amps (A)Measuring electric currentamps (A)The reading on an ammeter is in Smaller currents may be measured in milliamps (mA) or microamps (μA) 1 milliamp= 1 mA = 10^?3 A1microamp = 1 μA = 10^?6 A10^3 10^6 _____μA1 A =_____mA=Question 1What instrument is used to measure electric current? ammeterHow should it be connected in a circuit? in series. Draw its circuit symbol. Questions 2A circuit is set up ,in which a cell makes an electric current flow through a lamp.Two ammeters are included, one to measure the cur