A child slides down a plastic slide in a playground. The child is wearing a polyester outfit, and the slide is made of smooth plastic. As the child slides down, they gain an electric charge.
Explain how the child gains an electric charge.
When the child reaches the bottom of the slide, they touch a metal handrail. There is a spark and the child receives a small electric shock. The spark lasts for 40 ms and 0.0018 C of charge passes between the handrail and the child's hand.
State the equation linking charge, current, and time.
Calculate the average current in the spark. Give the unit.
The metal handrail is securely earthed to the ground. Explain why the child receives a shock even though the handrail is earthed.