Electrical Principles: Further Practice

Static charge, electromagnetism, and computing parallel resistance.

8 questions, free, marked as you go with a worked explanation on every one.

What this covers

Rubbing a balloon on your hair transfers electrons from your hair to the balloon. What charge does the balloon end up with?
Two objects with the same type of electric charge are brought close together. What happens between them?
Two resistors of 6 Ω and 3 Ω are connected in parallel. What is the total resistance of the combination, in ohms?
Compared to a single resistor used alone, adding a second resistor in parallel with it does what to the total resistance of the combination?
A wire carries a current of 0.5 A. How much charge passes a point in the wire in 20 seconds, in coulombs? (Use charge = current times time.)
An electromagnet is made by wrapping wire around an iron core and connecting it to a battery. Which change would make the electromagnet stronger?
Use the table below, showing the voltage measured across three lamps wired in series in the same circuit. What is the supply voltage of the circuit, in volts?
A technician touches a doorknob after walking across a carpet and feels a small shock. Which best explains why this happens?