Lecture 1

Question 1

Requirements for a circuit

Answer 1

Closed Conducting Path and Energy Source

Question 2

Magnitude of current is a function of what?

Answer 2

Vi, R tissues, and contact interference

Question 3

Impedance of dry skin

Answer 3

100,000-300,000 ohms/cm2

Question 4

Impedance of wet skin

Answer 4

1000-3000 ohms/cm2

Question 5

Biological effects of current are a function of what?

Answer 5

frequency, magnitude, duration, individual size, type of contact

Question 6

Let go current

Answer 6

5-20 mA

Question 7

Threshold of perception

Answer 7

min 0.5 mA (0.083 mA with gel)

Question 8

Severe Burns

Answer 8

greater than 10 amps

Question 9

Current thresholds increase with what?

Answer 9

body mass

Question 10

Macro shock occurs when?

Answer 10

current is applied at two points on the surface of the body

Question 11

safety limit of macroshock

Answer 11

5 mA

Question 12

Microshock occurs when?

Answer 12

when current is applied directly to the heart

Question 13

Safety limit of microshock

Answer 13

10 microA

Question 14

R patient

Answer 14

Rc1+Rb+Rc2

Question 15

Leakage Current is?

Answer 15

Current flow between adjacent isolated conductors at different potentials

Question 16

GFCI

Answer 16

Ground Fault Circuit Interrupt

Question 17

Chassis leakage for device not intended for patient contact

Answer 17

500 microA

Question 18

Chassis leakage for device with non-isolated patient leads

Answer 18

100 microA

Question 19

Chassis leakage for device with isolated patient leads

Answer 19

100 microA

Question 20

Patient lead leakage for device with non-isolated patient leads

Answer 20

50 microA

Question 21

Patient lead leakage for device with isolated patient leads

Answer 21

10 microA

Question 22

resistance between ground pin of plug and equipment and exposed metal objects

Answer 22

less than 0.15 ohms

Question 23

leakage current should be:

Answer 23

less than 10 to 500 microA