A-level Physics (Advancing Physics)/Current/Worked Solutions

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1. 10 coulombs flow past a point in a wire in 1 minute. How much current is flowing through the point?

I = \frac{10}{60} \approx 0.17\mbox{ A}

2. How long does it take for a 2A current to carry 5C?

2 = \frac{5}{t}

t = \frac{5}{2} = 2.5\mbox{ s}

Stromteiler.svg

3. In the diagram on the right, I = 9A, and I1 = 4.5A. What is the current at I2?

9 = 4.5 + I2

I2 = 4.5 A

4. What would I equal if I1 = 10A and I2 = 15A?

I = 10 + 15 = 25A

5. In the diagram on the right, in 5 seconds, 5C of charged particles flow past I1, and 6.7C flow past I2. How long does it take for 10C to flow past I?

\frac{10}{t} = \frac{5}{5} + \frac{6.7}{5} = 2.34

t = \frac{10}{2.34} \approx 4.27\mbox{ s}