An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?
Answer (2)
Start with the given formula: K = L MN .
Divide both sides by L N to isolate M : L N K = L N L MN .
Simplify the equation: M = L N K .
The formula for M is M = L N K .
Explanation
Understanding the Problem We are given the formula K = L MN and we want to isolate M to find its formula in terms of K , L , and N .
Isolating M To isolate M , we need to divide both sides of the equation by L N . This gives us: L N K = L N L MN
The Formula for M Simplifying the right side of the equation, we get: L N K = M Thus, the formula for M is: M = L N K
Selecting the Correct Option Comparing our result with the given options, we see that option C matches our derived formula.
Examples
In physics, if you know the total energy (K) of an object and have formulas for its length (L) and mass (N) that depend on other variables, you can find the object's momentum (M) using the formula derived. For example, if K represents energy, L represents a length-related parameter, and N represents mass, then M could represent momentum. Rearranging the formula allows you to calculate momentum directly from known or measurable quantities.
A current of 15.0 A flowing for 30 seconds results in approximately 2.81 billion billion electrons passing through the device. The total charge calculated is 450 coulombs, and using the charge of a single electron, we find the number of electrons. This highlights the significant number of electrons involved in electrical flow even for a brief period.
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