Physics Review Question Unit: Electricity Year: 1996 Question#: 31 Question: In a lightning strike, a charge of 18 coulombs is transferred between a cloud and the ground in 2.0 x 10-2 second at a potential difference of 1.5 x 106 volts. What is the average current produced by this strike? (1 ) 3.6 x 10-1 A (2 )9.0 x102 A (3 ) 3.0 x104A (4 ) 7.5 x107A What is this question really asking? Explanation by: Jennifer I [ Return to question menu ] Answer 1 3.6 x 10-1A INCORRECT This is the product of charge and time which does relate to current but is not a familiar equation and does not produce the correct units. return to top Answer 2 9.0 x 102 CORRECT Current (I)= charge/ time= 18 coulombs/2.0 x10-2s = 9.0 x 102 A Potential Difference is not needed. return to top Answer 3 3.0 x 10 4 A INCORRECT This is the product of charge and potential difference which does not deal with the time factor. Since current is a measurement of the amount of charge that passes a certain point, it must be restricted by a time limit which must show up inthe calculations. return to top Answer 4 7.5 x 10 7 A INCORRECT This value can not be achieved using the given data. return to top What's this question really asking? What is the current of a lightning strike with a charge of 18 coulombs which travels for 2.0 x 10-2 seconds and has a potential difference of 1.5 x 10 2 volts? return to top |
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