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Battery Modelling

Age 16 to 18
Challenge Level Yellow star
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A battery is modelled as a $24\mathrm{V}$ EMF in series with an internal resistance of $2\Omega$. The battery is being charged by a constant current source as shown in the network below. The ammeter, used to measure the current through the battery, has a voltage drop of $2\mathrm{V}$ at full range scales. Here it is set to a $20\mathrm{A}$ range and reads a current of $2\mathrm{A}$.

What is the value of the constant current supplied?

What fraction of the input power is supplied to the battery?

What current would flow into the battery if we now replaced the ammeter with a wire of zero impedance?



 

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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