Question 22N.1.HL.TZ0.36
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1.HL.TZ0.36 |
| Level | HL | Paper | 1 | Time zone | TZ0 |
| Command term | Question number | 36 | Adapted from | N/A |
A student states three facts about the time constant of a resistor-capacitor series circuit.
I. It is the time required for the capacitor to be charged through the resistor to a voltage of 0.632 V from an initial value of zero, where V is the voltage of the source.
II. It is the time required for the capacitor to be discharged through the resistor to a voltage of 0.632 V, where V is the initial voltage of the capacitor.
III. It is the product of the resistance of the resistor and the capacitance of the capacitor.
Which statements are correct?
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
[1]
B
Alternative C was picked more often than the correct B. Awareness of graphs representing charging and discharging of a capacitor helps to figure out the correct answer. Under discharge and during one time constant, the voltage decreases to less than 50% of the initial value (more exactly, to e−1 = 0.368 of the initial voltage), so statement II is incorrect.