Question

Estimate the value of resistances needed to make a variable timer for intermittent windshield wipers: one wipe every 15 s, 8 s, 4 s, 2 s, 1 s. Assume the capacitor used is on the order of 10 μF .

Part A

Estimate the mininum value of the resistance.

Express your answer to one significant figure and include the appropriate units.

Part B

Estimate the maximum value of the resistance.

Express your answer to one significant figure and include the appropriate units.

please show your work, thank you!

Answer 1

θ = R * C
15s --- R = θ / C = 15 / 10x 10^-6 = 1.5x 10^6Ω-----1500 kΩ
8s------R = 8 / 10x 10^-6 = 0.8x 10^6 Ω ----------------800 kΩ
4s------R = 4 / 10x 10^-6 = 0.4x10^6 Ω -------------------400kΩ
2s------R = 2 /10x 10^-6 = 0.2x 10^6 Ω ------------------200 kΩ
1s -----R = 1 / 10x10^-6 = 0.1x 10^6 Ω---------------------------100 kΩ

Part A

Answer : 100 kΩ ( min)

Part B

Answer: 1500 kΩ (max)