13. For each of the following cases for an RLC circuit, does the resonance frequency increase, decrease, or stay the same? If it changes, tell by what factor.

(a) Only the capacitance is changed – it is quadrupled.

(b) Only the inductance is changed – it is increased by nine times.

(c) Only the resistance is changed – it is increased by three times.

(d) Both the inductance and capacitance are doubled; nothing else changes.