You sometimes create a spark when you touch a doorknob after shuffling your feet on a carpet. why? the air always has a few free electrons that have been kicked out of atoms by cosmic rays. if an electric field is present, a free electron is accelerated until it collides with an air molecule. it will transfer its kinetic energy to the molecule, then accelerate, then collide, then accelerate, collide, and so on. if the electronβs kinetic energy just before a collision is 2.0Γ10β18 j or more, it has sufficient energy to kick an electron out of the molecule it hits. where there was one free electron, now there are two! each of these can then accelerate, hit a molecule, and kick out another electron. then there will be four free electrons. in other words, as shows below, a sufficiently strong electric field causes a "chain reaction" of electron production. this is called a breakdown of the air. the current of moving electrons is what gives you the shock, and a spark is generated when the electrons recombine with the positive ions and give off excess energy as a burst of light.
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Physics, 21.06.2019 15:30
Taylor's experiment: 1. accurately measured the speed of light 2. locked together the phases of two light sources so that the interference pattern would not shift 3. showed that man's reaction time was much slower than the speed of light 4. showed that individual photons have wave characteristics
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Physics, 22.06.2019 03:50
Which statement correctly describes a step-up transformer? a. it increases the amount of electric energy available. b. it increases the voltage of an electric current. c. it changes direct current into alternating current. d. it has more loops of wire in its primary coil.
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Physics, 22.06.2019 19:50
Ahuge (essentially infinite) horizontal nonconducting sheet 10.0 cm thick has charge uniformly spread over both faces. the upper face carries +95.0 nc/m2 while the lower face carries -25.0 nc/ m2. what is the magnitude of the electric field at a point within the sheet 2.00 cm below the upper face? (Ξ΅0 = 8.85 Γ 10-12 c2/n Β· m2)
Answers: 1
You sometimes create a spark when you touch a doorknob after shuffling your feet on a carpet. why?...
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