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

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?

$2={\frac {5}{t}}$

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

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?

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

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