Physics and Astronomy Outreach Program at the University of British Columbia

1. Electricity Generation Generating Electricity Multiple-Choice Questions Physics and Astronomy Outreach Program at the University of British Columbia

2. Electricity Generation Question 1 If the wire was moved in the direction of the arrow, what would happen to the charges in the wire? v +ve charges pushed to a, -ve charges pushed to b. +ve charges pushed to b, -ve charges pushed to a. +ve charges pushed to c, -ve charges pushed to d. +ve charges pushed to d, -ve charges pushed to c. Nothing a c d b Uniform B field (pointing into the page) Physics and Astronomy Outreach Program at the University of British Columbia

3. Electricity Generation Question 1 Answer If the wire was moved in the direction of the arrow, what would happen to the charges in the wire? v +ve charges pushed to a, -ve charges pushed to b. +ve charges pushed to b, -ve charges pushed to a. +ve charges pushed to c, -ve charges pushed to d. +ve charges pushed to d, -ve charges pushed to c. Nothing a c d b Uniform B field (pointing into the page) Physics and Astronomy Outreach Program at the University of British Columbia

4. Electricity Generation Question 1 Explanation Here, we see that the velocity is perpendicular to the magnetic field. We know therefore, that there will be a force that pushes the –ve charges in a direction perpendicular to BOTH the velocity AND the magnetic field – either toward a or toward b. To determine which of the two directions, use the right hand rule point your fingers in the direction of the field (into the page), face your palm in the direction of the velocity (to the left) and your thumb will point in the direction of motion of the –ve charges : toward a. v a c d b Uniform B field (pointing into the page) Physics and Astronomy Outreach Program at the University of British Columbia

5. Electricity Generation Question 2 If the wire was moved in the direction of the arrow, what would happen to the charges in the wire? v +ve charges pushed to a, -ve charges pushed to b. +ve charges pushed to b, -ve charges pushed to a. +ve charges pushed to c, -ve charges pushed to d. +ve charges pushed to d, -ve charges pushed to c. Nothing d a b c Uniform B field (pointing into the page) Physics and Astronomy Outreach Program at the University of British Columbia

6. Electricity Generation Question 2 Answer If the wire was moved in the direction of the arrow, what would happen to the charges in the wire? v +ve charges pushed to a, -ve charges pushed to b. +ve charges pushed to b, -ve charges pushed to a. +ve charges pushed to c, -ve charges pushed to d. +ve charges pushed to d, -ve charges pushed to c. Nothing d a b c Uniform B field (pointing into the page) Physics and Astronomy Outreach Program at the University of British Columbia

7. Electricity Generation Question 2 Explanation Here, we see that the velocity is perpendicular to the magnetic field. We know therefore, that there will be a force that pushes the –ve charges in a direction perpendicular to BOTH the velocity AND the magnetic field – either toward a or toward b. To determine which of the two directions, use the right hand rule point your fingers in the direction of the field (into the page), face your palm in the direction of the velocity (to the left) and your thumb will point in the direction of motion of the –ve charges : toward a. v d a b c Uniform B field (pointing into the page) Physics and Astronomy Outreach Program at the University of British Columbia

8. Electricity Generation Question 3 If the wire was moved in the direction of the arrow, what would happen to the charges in the wire? v a +ve charges pushed to a, -ve charges pushed to b. +ve charges pushed to b, -ve charges pushed to a. +ve charges pushed to c, -ve charges pushed to d. +ve charges pushed to d, -ve charges pushed to c. Nothing c d b Uniform B field (pointing OUT OF the page) Physics and Astronomy Outreach Program at the University of British Columbia

9. Electricity Generation Question 3 Answer If the wire was moved in the direction of the arrow, what would happen to the charges in the wire? v a +ve charges pushed to a, -ve charges pushed to b. +ve charges pushed to b, -ve charges pushed to a. +ve charges pushed to c, -ve charges pushed to d. +ve charges pushed to d, -ve charges pushed to c. Nothing c d b Uniform B field (pointing OUT OF the page) Physics and Astronomy Outreach Program at the University of British Columbia

10. Electricity Generation Question 3 Explanation Here, we see that the velocity is perpendicular to the magnetic field. We know therefore, that there will be a force that pushes the –ve charges in a direction perpendicular to BOTH the velocity AND the magnetic field – either toward a or toward b. To determine which of the two directions, use the right hand rule: point your fingers in the direction of the field (into the page), face your palm in the direction of the velocity (to the left) and your thumb will point in the direction of motion of the –ve charges : toward b. v a c d b Uniform B field (pointing OUT OF the page) Physics and Astronomy Outreach Program at the University of British Columbia

11. Electricity Generation Question 4 Which of the following will NOT light up the bulb? Option A Option B Option C Option D. Physics and Astronomy Outreach Program at the University of British Columbia

12. Electricity Generation Question 4 Answer Which of the following will NOT light up the bulb? Option A Option B Option C Option D. Physics and Astronomy Outreach Program at the University of British Columbia

13. Electricity Generation Question 4 Explanation In situation C, the wires are moving but the + charges in each wire will be pushed outward (radially), so no electricity will flow around the loop. In situation D, all the charges in the top half will be pushed down, and all the charges in the bottom half will be pushed up. These pushes will just cancel out, and again nothing will flow around the loop. Physics and Astronomy Outreach Program at the University of British Columbia

14. Electricity Generation Question 5 Which of these will light the bulb most strongly? Option A Option B Option C Option D. Physics and Astronomy Outreach Program at the University of British Columbia

15. Electricity Generation Question 5 Solution Which of these will light the bulb most strongly? Option A Option B Option C Option D. Physics and Astronomy Outreach Program at the University of British Columbia

16. Electricity Generation Question 5 Explanation Situation B will light the bulb most strongly: We get the best results when one side of the loop is in a field Upwards, and the other side is in a field Downwards. This way the pushes on the charges push in the same direction AROUND the loop. Physics and Astronomy Outreach Program at the University of British Columbia

17. Electricity Generation More Information: The right hand rule More information on the right hand rule used to answer the previous questions can be found on the Hypherphysics site: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html Physics and Astronomy Outreach Program at the University of British Columbia