Suppose a photometric sensor outputs 0.005 V per lux and is connected to the mbe

Question

Suppose a photometric sensor outputs 0.005 V per lux and is connected to the mbeds analog to digital subsystem. It is readable through an Analogln object named photometer. Which of the following instructions would compute the instantaneous (not average) light level (in lux): Many lights flicker in sync with the AC power system. This flickering is usually too high of a frequency to be noticed by the human eye, but can be detected by a photometric sensor. When attempting to measure perceived illumination, the instantaneous light level must be digitally low-pass filtered to remove the effect of this flicker. Which of the following declarations and instructions would cause the interrupt function filter to be automatically called at the rate of 240 times per second?

Explanation / Answer

29. As the photosensor o/p=0.005 V / lux

Hence, to compute instantaneous light the instruction will be

lux=photometer.read();

as it is mentioned that the output should be in lux so the instruction used will be

b) lux=photometer.read()*0.005;

d) lux=photometer.read()*3.3*0.005;

30.

e. Timer timer;

while(timer.read()<1/240)

{

filter();

}

and

a) Ticker ticker;

ticker.attach(filter, 1/240);

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