Flashcards
current and charge
Flashcards do conjunto (28)
- 1what is a lightning boltthe path taken by billions and billions of electrons travelling from the cloud to the ground, this flow of charged particles produces and electric current
- 2how is electric current measured and what is the equationamperes, current = change in charge / change in time
- 3what is the electric currentthe amount of charge passing a given point in a circuit per unit time
- 4what is electric chargea physical property that measured how charged something is
- 5what is coulombthe electric charge flowing past a point in one second when there is a current of 1 A
- 6what is a charge carrierany particle that has an electric charge
- 7what is a relative chargean integer that represents the charge as a multiple of e
- 8what is the elementary constant1.60 x 10 *-19, e, the actual charge of a proton and negative version is the actual charge of an electron
- 9what is the actual charge of the aluminium 3+ ion1.60 x 10*-19 x 3 = 4.8 x 10 *-19
- 10what are the steps to calculating the number of electrons passing through one point in a circuit/component in a given timefind the charge with the equation I = ΔQ / Δt, and then divide this by the elementary constant to find the number of electrons
- 11how do you find the net charge of an objectnet charge = ±ne
n is the number of electrons transferred, e is the elementary constant - 12why is the charge on an object described as being quantisedbecause it can only by integer multiples e
- 13what was Millikan's experiment1909, millikan and fletcher carried out the oil drop experiment, where he analysed the motion of electrically charged oil droplets between two oppositely charged parallel plates
- 14what did millikan's experiment discoversome oil droplets were held still as the downward gravitational force was balanced by the upward attractive electrostatic force, others drifted through the electric field, & so he could calculate the charge on many droplets, which he realised was quantised, multiples of the elementary charge, and so calculated the actual charge of the particles
- 15what are the most common charge carriers in metals and liquidsin metals, electrons, in liquids, ions
- 16describe the electric current in metalsfree electrons move through the wire, randomly colliding with the positive ions as they drift past them, around the positive metal ions. a regular crystal structure or lattice of positive ions, surrounded by free/delocalised electrons. the positive ions are in fixed points, vibrating
- 17name one way to make electrons move in a wiremake one end of the wire positive and one end negative. the electrons in the metal of the wire are attracted towards the positive end, and so move through the wire as an electric current
- 18what can a larger current be due toa greater number of electrons moving past a given point each second. or the same number of electrons moving faster through the metal
- 19what direction do all electric currents travel inpositive to negative, apart from in metals where they move in the opposite direction
- 20what are electrolytes, and what carry the chargeliquids that carry an electric current, molten ionic compounds or ionic solutions, which is a flow of ions and not electrons
- 21name facts about the conductivity of pure water and water in taps and riverspure water is a very good insulator, but water in taps and rivers is an ionic solution - it contains dissolved ions and so can carry electric current
- 22name a common example of ionic solution and explain itsalt, sodium chloride NaCl, dissolved in water. the salt separates into positively charged sodium ions (cations) Na+, and negatively charged chlorine ions (anions) Cl-
- 23what are the positive and negative electrodes calledpositive is the anode and negative is the cathode
- 24what are the positive and negative ions called in ionic solutionspositive is
- 25describe what happens during electrolysisthe anode and cathode are placed in the solution, the Na+ ions move toward the cathode and the Cl- ions move toward the anode, this movement of ions is a flow of charge, aka electric current
- 26what happens when the ions during electrolysis reach their electrodesthe positive Na+ ions reach the cathode and accept an electron, when the negative Cl- ions reach the anode they donate and electron, so the electrons can flow through the metal part of the circuit
- 27what is an ammeter and where is it placed in a circuitit is a device used to measure the electric current at any point in a circuit, it is placed in series in the circuit.
- 28what affect should the ammeter have on resistance and current in a circuitthe ammeter should have the lowest possible resistance to reduce the effect they have on the current, an ammeter with high resistance would decrease the current it should be measuring. the ideal ammeter would have zero resistance, and no effect on the current it is measuring
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- physics A level (M4 Chapter 8 current and charge) FlashCards sobre current and charge, criado por lizabeth rawson em 15-09-2020.
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- lizabeth rawson
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