Think of a capacitor as a bucket you can fill with charge. It's not so far fetched; the first capacitors were glass jars lined with metal foil (Leyden jars) and until the 1920s, capacitance was measured in "jars" (1 jar is about 1100pf!)
The book is correct - the capacitance is always there and frequency has nothing to do with it. However the charge it can store is proportional to voltage (as if charge was a gas you could compress, not a liquid. And indeed voltage used to be called "pressure".)
Q (charge) = C * V.
But now consider an AC voltage across the capacitor. In one AC cycle, you fill the bucket, and then empty it. You have transferred charge Q out of the voltage source.
Now the more often you do that, the more charge you transfer in a second. Charge per second is simply current, so the higher the frequency, the higher the current.
Current through the capacitance increases with frequency - so the "bucket" conducts better - i.e. its conductance is proportional to frequency - but the capacitance is the same.
Reactance is the inverse of conductance, so reactance decreases with frequency.
(The pedant will note that I should have used the word "susceptance" in place of "conductance" here;
susceptance = 1/reactance
conductance = 1/resistance
and for completeness,
admittance = 1/impedance
but I think that would only have obscured the basic idea)
I've never seen a semiconductor destroyed by cold weather but operating them below their rated temperature can sure cause them to malfunction.
Years ago, we were using one particular brand of 7805 regulator that was rated for use at 0C through 70C. When used outdoors, it functioned as a very nice thermostat and turned OFF at about -20F. The cure was to replace it with a part that was rated to work cold.
Best Answer
The device FSQ0270 is an integrated controller for Switched Mode Power Supplies. The datasheet provides standard application circuit schematics.
When used in such a circuit, the device is fed with rectified mains voltage (unregulated DC half-sine wave), and generates the pulses required to drive a suitable transformer at 100 KHz, to provide a desired DC output voltage.
The Feedback pin accepts input from an optocoupler to sense the output current, and manipulates the output cycle-by-cycle (at each pulse, at 100 KHz i.e. 100,000 times a second) suitably to provide the designed voltage, with current limiting.
The part also has built-in safety features such as overload protection, overheat protection, and over- and under-voltage protection.
Some context on why the question was raised, would help provide a more relevant response.