Answer :
To determine how long it takes to serially enter eight bits into a shift register with a 200 kHz clock frequency, let's break down the steps and do the calculations:
Understand Clock Frequency: The clock frequency is given as 200 kHz. This means that the clock ticks 200,000 times per second.
Calculate the Time for One Clock Cycle: Since the frequency is 200,000 Hz, the period (the time for one cycle) is calculated using the formula:
[tex]\text{Time for one cycle} = \frac{1}{\text{Frequency}}[/tex]
Substituting the given frequency:
[tex]\text{Time for one cycle} = \frac{1}{200,000} = 5 \times 10^{-6} \text{ seconds} = 5 \text{ microseconds} = 5000 \text{ nanoseconds} = 5000000 \text{ picoseconds}[/tex]Calculate the Time for Eight Bits: Since it takes one clock cycle to enter each bit serially, and we need to enter eight bits, the total time required is:
[tex]\text{Total time for 8 bits} = 8 \times \text{Time for one cycle} = 8 \times 5 \text{ microseconds} = 40 \text{ microseconds} = 40000 \text{ nanoseconds}[/tex]
Therefore, eight bits can be serially entered into the shift register in 40000 nanoseconds.
To conclude, the correct multiple-choice answer is 40000 ns.