1. Agenda Next Week –Finish 29, No Quiz –Review Following –Exam II on Monday (2 weeks) –April 6 th [Or previous Friday if prefer] Sections –27.1-27.8 –28.1-28.5, skim28.8: No worry about “how” Mag fields arise –29.1-29.5

2. Today Induction –Sliding bar –Open ?’s

3. Sliding System Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir.

4. Sliding System Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. What Happens when you let go? 1 st – Ignore Induction Then identify what Induction will do

5. Consider No Induction… Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. What Happens when you let go? “Loop” Increases in size Area Increases  Flux Increases

6. Induction Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. What Happens when you let go? Area Increases  Flux Increases Voltage Induced Current Induced in “Loop” Light Bulb Turns on Current Direction? Falls Down a < g

7. Induction Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. What Happens when you let go? Area Increases  Flux Increases Voltage Induced Current Direction like so What is the acceleration of the bar? What forces act on the bar? Current

8. Induction Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. What Happens when you let go? Area Increases  Flux Increases Voltage Induced Current Direction like so What is the acceleration of the bar? Direction of each force? Current

9. Induction Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. What Happens when you let go? Area Increases  Flux Increases Voltage Induced Current Direction like so What is the acceleration of the bar? Direction of each force? Acceleration < g Current FGFG FBFB

10. Induction Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. What Happens when you let go? Area Increases  Flux Increases Voltage Induced Current Direction like so What is maximum magnetic force? Current FGFG FBFB

11. Induction Bar free to slide up/down Slides on metal rails Gravity pulls down Light Bulb on Top Uniform B +Z dir. Problem Assume really long rails What is max speed of bar? Need mass, resistance, geometry, field Current FGFG FBFB