15.At a manufacturing site in company XYZ during an 8- Hour shift, a worker is exposed to 100PPM of a chemical for hours and to 150 PPM for 2 hours. The TWA exposure for this worker is? 16. Two resistors with resistance of 5 and 10 ohms are arranged in parallel in a circuit having a potential difference of 110 Volts. The amount of current drawn by the two resistors will be? 17.You are standing 2 feet from a radiation source. How far should you move away to reduce your exposure to 1/100 of the original value? 18. The volumetric flow rate of air through a centrifugal fan is 1000 ft³ per minute at 500 RPM. If we increase the impeller speed to 4000 RPM, how much air can we pump through this fan?
15. The TWA exposure for the worker can be calculated using the formula:
TWA = ((C1 x T1) + (C2 x T2) + ... + (Cn x Tn)) / Total Time
Where:
C1, C2, etc. = concentration of the chemical at different times
T1, T2, etc. = time exposed to each concentration
In this case:
T1 = 8 hours
C1 = 100 PPM
T2 = 2 hours
C2 = 150 PPM
TWA = ((100 x 8) + (150 x 2)) / 10
TWA = (800 + 300) / 10
TWA = 110 PPM
Therefore, the TWA exposure for the worker is 110 PPM.
16. The total resistance of resistors in parallel can be calculated using the formula:
1/RTotal = 1/R1 + 1/R2
1/RTotal = 1/5 + 1/10
1/RTotal = 2/10 + 1/10
1/RTotal = 3/10
RTotal = 10/3 ohms
The current drawn by the resistors can be calculated using Ohm's Law:
I = V / R
I = 110 / (10/3)
I = 33/10 amps
I = 3.3 amps
Therefore, the amount of current drawn by the two resistors is 3.3 amps.
17. The relationship between radiation exposure and distance follows the inverse square law, which states that the intensity of radiation is inversely proportional to the square of the distance from the source.
Therefore, to reduce exposure to 1/100 of the original value, the new distance can be calculated using the formula:
(new distance)^2 = (original distance)^2 * (original intensity) / (new intensity)
( new distance)^2 = 2^2 * 1 / 100
(new distance)^2 = 4 / 100
(new distance)^2 = 0.04
new distance = √0.04
new distance = 0.2 feet
Therefore, the worker should move to a distance of 0.2 feet to reduce exposure to 1/100 of the original value.
18. The relationship between volumetric flow rate and fan speed in a centrifugal fan is directly proportional. Therefore, to calculate the new volumetric flow rate at 4000 RPM:
New flow rate = (New RPM / Original RPM) x Original flow rate
New flow rate = (4000 / 500) x 1000
New flow rate = 8 x 1000
New flow rate = 8000 ft³ per minute
Therefore, by increasing the impeller speed to 4000 RPM, the fan can pump 8000 ft³ per minute of air.