Question

The time constant for RC circuit with the values of R1 and C1 is 5ms. What will be the time constant for a new RC circuit with the values: R2=10R1 and C2 = 0.5C1.

a. 2.5ms
b. 15.5ms
c. 50ms
d. 25ms
e. 15ms

Answer 1

d. 25 ms

Step-by-step explanation:

• In a RC circuit we call time constant to the product of the resistance times the capacitance, which represents the time when the charge reaches to the 63% of the final value, as follows:

`\tau_(1) = R_(1) *C_(1) = 5 ms (1)`

• If we have a new circuit with new values for R and C, the time constant will be defined in the same way, as follows:

`\tau_(2) =10* R_(1) *0.5*C_(1) = 5*(R_(1)* C_(1)) = 5* \tau_(1) = 5* 5 ms = 25 ms (2)`