APPC RC Circuit Wrapup

RC Circuits

Charging & Discharging

By Kathy Dao

Open Ended

Compare and contrast the Q vs t graph for charging and discharging the RC Circuit.

Compare Q₀ min and max at t₀ and their respective values at t=τ

Open Ended

Compare and contrast the I vs t graph for charging and discharging the RC Circuit.

Why is the I graph symmetrical about the x-axis?

Hint: Think of the direction that current moves during charging and discharging phase.

Open Ended

Finally, compare and contrast the V vs t graph for charging and discharging the RC Circuit.

Compare V min and max at t₀ and their respective values at t=τ

Multiple Choice

In the RC circuit, the time constant (τ) for the circuit is:

• τ = R × C
• τ = R / C
• τ = C × R
• τ = R² × C

Multiple Choice

When will the capacitor be fully charged?

• When voltage across capacitor is zero

• When voltage is infinity

• When the voltage across the capacitor is equal to the supply voltage

• When capacitor voltage is equal to half the supply voltage

Multiple Choice

In the RC discharging circuit, time constant (τ) is the time taken by the charge of the capacitor to reach ---------------- of the initial charge.

• 63%

• 37%

• 50%

• 67%

Multiple Choice

Which of the following statement are CORRECT about the FIGURE 17.2?

• Charge across $$C_2$$ and $$C_3$$ are same.

• Voltage across $$C_1$$ and $$C_2$$ are same.

• Total capacitance is 2.25 $$\mu$$ F

• Total voltage across $$C_2$$ and $$C_3$$ are 16 V

Multiple Choice

How long does it take for a capacitor to charge fully?

Hint: Use 99.9% as a fully charged.

• 1τ

• 10τ

• 5τ

• 3τ

Labelling

Label which part of the graph is the capacitor charging and discharging

Drag labels to their correct position on the image

Charging

Constant V

Discharging

Labelling

Label which part of the graph is the capacitor charging and discharging

Drag labels to their correct position on the image

Discharging

Zero current

Charging

Charging Equations

​​Discharging Equations

Open Ended

Compare and contrast the Charging and Discharging RC circuit Equations

Multiple Choice

Which RC circuit is used during the Charging phase?

• A

• B

Multiple Choice

Which RC circuit is used during the Discharging phase?

• A

• B

Multiple Choice

The capacitance C is charged through a resistor R. The time constant of the charging circuit is given by

• C/R

• 1/RC

• RC

• R/C

Multiple Choice

Calculate the time constant of a series RC circuit consisting of a 100microF capacitor in series with a 100ohm resistor.

• 0.1 s

• 0.1 ms

• 0.01 s

• 0.01 ms

Poll

Do you understand the similarities and differences of Charging and Discharging an RC Circuit?