With the switch closed, how does the voltage across the 20-ω resistor compare to the voltage across the 10-ω resistor?

In electricity, the most famous and basic equation is the Ohm's Law which relates the parameters voltage, current and resistance. One form of this law as written in equation is V = IR, where V is the voltage in volts, I is the current in amperes and R is the resistance in ohms. These parameters depends in the arrangements, whether it's series or parallel.

In a series connection, the voltage is greater across a high-resistance resistor. Therefore, the voltage is much greater for the 20-ohm resistor. However, if it is a parallel circuit, the voltage is just the same for both resistors.