Electricity, magnetism, electric circuits, and their physical laws; light-specific phenomena belong in Optics. Energy-source technology belongs in Renewable Energy.
Test your knowledge with these top questions!
Why does a balloon rubbed on hair stick to a wall?
The wall starts neutral, but the charged balloon pushes its charges apart and pulls opposite charges to the surface.
In a laser printer, static electricity first attracts toner powder to which part?
A laser changes the drum's charge pattern, creating an invisible image that attracts toner before it transfers to paper.
Which ancient Greek philosopher noticed that rubbed amber attracts light objects?
Electricity takes its name from "elektron", the Greek word for amber, the resin Thales rubbed.
A static-electricity shock from a doorknob involves the sudden transfer of which particles?
Shuffling over carpet can leave your body with a charge imbalance that discharges as a spark when you touch metal.
Why can one household lamp be switched off while other lamps stay on?
Parallel wiring gives each lamp the full supply voltage rather than dividing it among the lamps.
Which force makes the shaft of a typical electric motor turn?
Current flowing through coils creates magnetic fields that push and pull on magnets or other coils inside the motor.
After a standard fuse blows, what must happen before the fuse can carry current again?
When excess current melts a fuse's thin metal link, cooling alone cannot close the gap.
Which metal commonly strengthens an electromagnet when placed inside the wire coil?
The coil lines up tiny magnetic regions in the iron, so the core adds its own magnetic field to the coil's field.
Why can a fuse with too high a current rating leave household wiring unprotected?
The appliance determines how much current it draws; a fuse's rating does not cap that current at a safe level.
Which pan material works on a standard induction cooktop without an added magnetic base?
A fridge magnet should cling firmly to a suitable pan's base, making the magnet a quick compatibility test.