Question

The timing device in an automobile's intermittent wiper system is based on an RC time constant and utilizes a 0.630 µF capacitor and a variable resistor. Over what range (in MΩ) must R be made to vary to achieve time constants from 1.50 to 20.0 s?

Answer 1

Range of the resistance is given as

`R_1 = 2.38 M ohm` to

`R_2 = 31.75 M ohm`

Step-by-step explanation:

As we know that the time constant is the product of capacitance and the resistance of the the circuit

So here we know that the range of the time constant is varying from 1.50 s to 20.0 s

so here we have

`C = 0.630 \mu F`

now we have

`R_1(0.630 \mu F) = 1.50`

`R_1 = 2.38 M ohm`

now another time constant is

`R_2 (0.630 \mu F) = 20.0`

`R_2 = 31.75 M ohm`