Question

The current supplied by a battery in a portable device is typically about 0.151 A. Find the number of electrons passing through the device in five hours.

Answer 1

Explanation:

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Answer 2

Answer:

n = 1.7*10²² electrons.

Explanation:

• As the current, by definition, is the rate of change of charge, assuming that the current was flowing at a steady rate of .151 A during the 5 hours, we can find the total charge that passed perpendicular to the cross-section of the circuit, as follows:

       $I =\frac{\Delta q}{\Delta t} \\ \\ \Delta q = I* \Delta t \\ \\ \Delta t = 5hs*\frac{3600s}{1h} = 18000 s$

       ⇒ Δq = I * Δt = 0.151 A * 18000 s = 2718 C

• As this charge is carried by electrons, we can express this value as the product of the elementary charge e (charge of  a single electron) times the number of electrons  flowing during that time, as follows:

         Δq = n*e

• Solving for e:

        $n = \frac{\Delta q}{e} =\frac{2718C}{1.6-19C} = 1.7e22 electrons.$