lecture14

# 26 2013 9 in the picture there are two particles

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Unformatted text preview:   Device used to accelerate charged objects   The dee’s   Made of metal (copper here)   Electric field inside is 0   Uniform magnetic field   Between the dee’s there is a potential difference to accelerate the charge particles   Must alternate electric potential in order always accelerate and not decelerate Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 11   Alternating potential difference   Must alternate electric potential in order always accelerate   With what frequency? 2 v qvB0 = m r Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 12   Alternating potential difference   Must alternate electric potential in order always accelerate   With what frequency? 2 v qvB0 = m r ω v qB0 f= = = 2π 2π r 2π m Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 13   Let’s exam and re-write the qv part of the magnetic force. FB = qEnclosed vd × B   The full amount of moving charge in some length of wire will determine the size of the force on the wire. qEnclosed = N ( − e) ⎛ L⎞ qEnclosed vd = ( I Δt ) ⎜ ⎟ = IL ⎝ Δt ⎠ Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 14   The full amount of moving charge in some length of wire will determine the size of the force on the wire. qEnclosed vd = IL FB = qEnclosed vd × B = IL × B   When determining force direction, you still use the RHR! Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 15 What direction will the force on the currentcarrying wire be directed? A)  +x I B)  -x C)  +y y z D)  -y x E)  +z Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 16 What direction will the force on the currentcarrying wire be directed? A)  +x I B)  -x C)  +y y z D)  -y x E)  +z Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 17   Without current there will be no force   With opposite current directions comes forces in different directions   Check that these are correct with the RHR Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 18 Which wire will have the largest and which the smallest force acting on it? (Assume the wirelength is the same.) FB = IL × B ˆ ˆ ˆ I) B = B0 x II) B = B0 x III) B = B0 x I y y y x x x I 2I A) I, III B) II, I C) I, II D) II, III E) III, I Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 19 Which wire will have the largest and which the smallest force acting on it? (Assume the wirelength is the same.) FB = IL × B ˆ ˆ ˆ I) B = B0 x II) B = B0 x III) B = B0 x I y y y x x x I 2I A) I, III B) II, I C) I, II D) II, III E) III, I Physics 2B - Summer Session 2 - C. Palmer August 26, 2013 20   Motivation: we can use the torque on a wi...
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