31 July 2017
4.2 Charge on the Move
•Conductors cannot become charged when
electrons are free to move to Earth.
•Charge is carried by electrons moving
through conductors. This flow is called an
electric current.
•A build up of charge can produce sparks.
What is a water current?
Try to describe in less than 20
words what a water current is.
5 minutes!
In Denmark in 2004, 31 cows were killed by one bolt of lightning. They were
sheltering under a tree during a storm. Why is lightning more dangerous for
creatures with 4 legs than 2?
Electric current
• In an electric circuit electrons flow.
• Electrons have a ___________ charge.
• Positive charges can only move in a liquid
or gas.
electrons
Gold Leaf Electroscope
Diagram
This device measures charge. Electrons can flow
through the metal parts when a charged object is
brought near the metal cap. The gold leaf moves
because it has the ______ charge as the rod.
Surviving Lightning
Lightning is caused when the
charge on the cloud is connected
to Earth – We say the charge is
Earthed. The charge will take
the easiest route. Air is a bad
conductor. Most other materials
are better conductors.
A small current (.05A)
through the heart is
enough to stop it.
Why is a prayer position
the best position to adopt
in a lightning storm?
Dangerous Sports
Many people are killed every year playing
sports in thunderstorms. Some sports
are more dangerous than others.
Which are the most
dangerous sports in a
thunderstorm? Can
you explain why?
Answer the summary
questions on page 163
31 July 2017
4.2 Charge on the Move
•Conductors cannot become charged when
electrons are free to move to Earth.
•Charge is carried by electrons moving
through conductors. This flow is called an
electric current.
•A build up of charge can produce sparks.