Multiple-Choice Questions Human Body Electric Shock Multiple-Choice Questions Physics and Astronomy Outreach Program at the University of British Columbia

Question 1 Birds land on high voltage power lines, Electric Shock Question 1 Birds land on high voltage power lines, Why don’t they get shocked? The wires they land on are insulated. They are not touching ground so there is no potential difference across their bodies. Birds have large resistance Physics and Astronomy Outreach Program at the University of British Columbia 2

Question 1 solution Birds land on high voltage power lines, Electric Shock Question 1 solution Birds land on high voltage power lines, Why don’t they get shocked? The wires they land on are insulated. They are not touching ground so there is no potential difference across their bodies. Birds have large resistance In V=IR, V refers to a potential difference across the resistor(bird). Birds normally only touch the lines at one potential. Physics and Astronomy Outreach Program at the University of British Columbia 3

Question 2 If it is electrical current that hurts us, why Electric Shock Question 2 If it is electrical current that hurts us, why do the danger signs say ‘High Voltage’? It is a convention established before people understood what is actually dangerous. V= IR, as V increases, I increases High currents can not occur unless there are high voltages. Physics and Astronomy Outreach Program at the University of British Columbia 4

Question 2 Solution If it is electrical current that hurts us, why Electric Shock Question 2 Solution If it is electrical current that hurts us, why do the danger signs say ‘High Voltage’? It is a convention established before people understood what is actually dangerous. V= IR, as V increases, I increases High currents can not occur unless there are high voltages. Physics and Astronomy Outreach Program at the University of British Columbia 5

Question 3 Electric Shock If you touched both the hot wire from an outlet and the neutral wire simultaneously, would the GFCI turn off ? a) Yes b) No

Question 3 Solution Electric Shock If you touched both the hot wire from an outlet and the neutral wire simultaneously, would the GFCI turn off ? a) Yes b) No The magnetic flux through the sense coil stays at zero. No change in flux is detected compared to normal operating conditions. 7

Question 4 What is the main purpose of the magnetic core? Electric Shock What is the main purpose of the magnetic core? To hold the sense coil in place. b) To magnify the B-field inside the sense coil. c) To cause there to be a B-field inside the coil. 8

Question 4 Solution What is the main purpose of the magnetic core? Electric Shock What is the main purpose of the magnetic core? To hold the sense coil in place. b) To magnify the B-field inside the sense coil. c) To cause there to be a B-field inside the coil. 9