Electricity quiz

More questions about Electricity

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   How often does lightning strike the Empire State Building?

   Answer: About 23 times a year

   Why: During one storm the Empire State Building was struck eight times in just 24 minutes.

2. 2 Medium

   What happens to electric current as it passes through a bulb?

   Answer: Stays the same

   Why: What the bulb takes is energy: the voltage across it measures the energy each coulomb of charge gives up.

3. 3 Hard

   Which country splits its power grid between 50 Hz and 60 Hz?

   Answer: Japan

   Why: Eastern Japan's grid grew from German AEG generators running at 50 Hz, western Japan's from American General Electric ones at 60 Hz.

4. 4 Easy

   What flows through a metal wire as electric current?

   Answer: Electrons

   Why: Copper has about one free electron per atom, around 85 billion billion billion in every cubic meter of wire.

5. 5 Medium

   Which metal carries the power in most high-voltage overhead lines?

   Answer: Aluminum

   Why: An aluminum cable weighs about half as much as a copper one of the same resistance, though it has to be thicker.

6. 6 Hard

   What is it called when alternating current crowds near a wire's surface?

   Answer: Skin effect

   Why: At 50 Hz the effect is mild: in copper the current density only drops to about 37% of its surface value 9 mm down.