Question

The cause of a fire in a computer is described as an incorrectly wired circuit.

Which statement best explains the likely cause of the fire?

The wiring contained a short circuit, so the reduced resistance caused an increase in current.
The wiring contained an open circuit, so the reduced resistance caused an increase in current.
The wiring contained a closed circuit, so the current was redirected around the components that would have provided the proper resistance.
The wiring contained an open circuit, so the current was redirected around the components that would have provided the proper resistance.

Answer 1

"The wiring contained a short circuit, so the reduced resistance caused an increase in current."

Reason: a short circuit bypasses the intended resistances, so for a given supply voltage V the current I = V/R increases when R falls. The larger current produces much greater I^2R heating in conductors and components, which can cause overheating and ignition.