Top-down schematic · illustrative routes · no distance scale

LaptopPhoneCoffeeGoal

1. Both devices appear protected

A laptop-only rule can produce the same apparent success as an electronics rule.

PhoneCoffeeGoal

2. Remove the laptop

The unchanged rule offers no reason to keep away from the remaining phone.

PhoneCoffeeGoal

3. Broaden the rule

A further correction brings electronics into consideration. Demonstrations help set the tradeoffs.