A bird rests with both feet on the same overhead power line and does not touch the ground or another object. Why can the bird remain unharmed?
There is almost no potential difference between the bird's feet, so almost no current passes through its body.
The bird's feet are electrical insulators, so they stop charge from passing into the bird's body.
The line carries alternating current, which cannot transfer energy to the tissues in the bird's body.
The current carried by the overhead line is too small to cause any harm to the bird's tissues.
81 exam-style questions on Edexcel GCSE Physics 10.4 Mains electricity, covering 10.4.1 Direct and alternating current, 10.4.2 Live, neutral and earth wires; safety, 10.4.3 Mains wire potential differences and dangers, and 10.4.4 Power ratings and energy use. Each one has a worked solution and a mark scheme showing where the marks go.