A flywheel has a small magnet mounted on it. EAch time the magnet passes the coil, a voltage pulse is generated, which is passed to the c.r.o. The display of the c.r.o. is 10cm wide. The flywheel is rotating at a rate of about 3000 revolutions per minute.Why will the time base setting 10ms?cm dispaly clearly separate pulses on the screen?
To answer this question, we need to consider the relationship between the time base setting of the cathode ray oscilloscope (c.r.o.) and the rotational speed of the flywheel.
Before explaining further, let's understand the components involved:
1. Flywheel: It is a rotating disc with a small magnet mounted on it. As the flywheel spins, the magnet passes a coil, which generates voltage pulses.
2. Cathode Ray Oscilloscope: It is an electronic device used to visualize and analyze electrical signals. It has a screen with a certain width called the display width.
Now, let's address the question:
The width of the display on the c.r.o. is given as 10cm. To clearly separate the voltage pulses generated by the passing magnet, we need to ensure that each pulse fits within this width. Hence, the time base setting is important.
The time base setting determines the horizontal scale of the waveform displayed on the c.r.o. It controls how much time is represented by each centimeter (cm) on the display.
In this case, we need to find a time base setting that allows each pulse to be clearly visible within the 10cm width of the display.
Given that the flywheel is rotating at a rate of 3000 revolutions per minute, we can calculate the time taken for one revolution:
1 revolution = 1/3000 minutes
Since there are 60 seconds in a minute, we can convert this to seconds:
1/3000 minutes = (1/3000) x 60 seconds
Now, to understand why the time base setting should be 10ms (milliseconds), we need to find the time taken for one pulse. This depends on the number of pulses generated per revolution of the flywheel.
Let's assume there is only one pulse generated per revolution of the flywheel. In that case, the time taken for one pulse will be the time taken for one revolution.
Using the calculation above, the time taken for one pulse would be:
(1/3000) x 60 seconds = 0.02 seconds = 20 milliseconds (ms)
Since the display width is 10cm and we have determined that the time taken for one pulse is 20ms, we need to set the time base of the c.r.o. to a value equal to or greater than the time taken for one pulse to ensure clear separation of the pulses on the screen.
Therefore, a time base setting of 10ms would be appropriate as it is long enough to clearly display a pulse within the 10cm wide display of the c.r.o.
In summary, by understanding the rotational speed of the flywheel and the width of the c.r.o. display, we can determine the appropriate time base setting that allows the pulses generated by the passing magnet to be clearly separated and visible on the screen.
Rotation is 3000 rev per min.
F=1/T or T=1/F
F is measured in rev per second.
F=3000/60=50
T=1/50=0.02s
S to MS is x1000 so 0.02s => 20ms
Hence, it is appropriate to use 10ms/cm for a clear display of pulse.