A student wants to generate a square wave with 50% duty cycle and 1 Hz frequency using 555 timer IC. What is the value of external resistance(s) (in Ohm)?

To generate a square wave with 50% duty cycle and 1 Hz frequency using a 555 timer IC, we need to calculate the values of the resistors (R1 and R2) and the capacitor (C1).

The frequency (f) of the output signal is determined by the resistors and the capacitor, and can be calculated using the following formula:

f = 1.44 / ((R1 + 2R2) * C1)

Given that the duty cycle is 50%, R1 should be equal to R2. Therefore, the formula becomes:

f = 1.44 / (3R * C1)

We know that the frequency f is 1 Hz. Let's assume we have a standard capacitor value of 10 µF (microfarads), which is 0.00001 F (farads). We can substitute these values into the formula and solve for R:

1 = 1.44 / (3R * 0.00001)

Solving for R gives:

R = 1.44 / (3 * 1 * 0.00001) = 48,000 Ohms or 48 KOhms

So, the values of R1 and R2 should be 48 KOhms each.

Please note that the actual values may need to be adjusted based on the specific characteristics and tolerances of the components used.