How can you change the time constant if the capacitance of the circuit is fixed?

Question

How can you change the time constant if the capacitance of the circuit is fixed? (1)

Capacitors have many practical applications (camera flashes, smoothing AC 'ripples' on the DC supplied by power supplies, windshield wipers, etc.). There are several types of capacitor, but all types include plates separated by an insulator. As we saw in Electricity capacitors can hold charge. The more charge that a capacitor holds, the higher the voltage across it becomes. For a given capacitor, the amount of charge stored is directly proportional to the voltage across the plates, charge stored oc AV Q 3 constant X AV. The constant here is called Coulombs capacitance' and is defined C The units of capacitance are Farads AV Volts In the lab, you will look at the voltage across a capacitor as it loses charge. What kind of voltage change across a capacitor should you expect? The simplest answer is that as Q decreases, then AV must decrease so as to keep C AV constant. The real question then becomes, "what will we do physically to make Q decrease AV decrease)? The answer is that we'll connect one plate of the capacitor to the other as in the following diagram, We expect a current to flow (through the resistor) from one plate to the other. Some theoretical work leads us to expect current to be lot) 3loe RC where lo is a constant and t is the time

Explanation / Answer

We know that the time constant is defined as
T = RC
where T is the time constant
R is the resistance and C is the capacitance
As it is given that the capacitance of the circuit is fixed therefore we have to change the
Resistance of the circuit by usinng variable resistor to change the time constant.

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.