Example 3: A positively charged particle of mass m = 0.0004 g and charge q = 53 μC is moving horizontally towards the wire carrying current I at the instant shown in the figure. The speed of the particle is v= 3900 m/s. (a) What is the direction of the current to keep the charge floating at this instant? (b) What is the current? Here r = 0.3 m. Hint: Gravity is not negligible in this problem. You must consider the weight of the particle when you calculate magnetic force. Follow the steps below. Z (out) r I Steps: 1) Magnitude the magnetic force N; direction 2) Magnitude the magnetic field B calculated from the magnetic force at the location of the charge. T; RHR#1 direction

Example 3: A positively charged particle of mass m = 0.0004 g and charge q = 53 μC is moving horizontally towards the wire carrying current I at the instant shown in the figure. The speed of the particle is v= 3900 m/s. (a) What is the direction of the current to keep the charge floating at this instant? (b) What is the current? Here r = 0.3 m. Hint: Gravity is not negligible in this problem. You must consider the weight of the particle when you calculate magnetic force. Follow the steps below. Z (out) r I Steps: 1) Magnitude the magnetic force N; direction 2) Magnitude the magnetic field B calculated from the magnetic force at the location of the charge. T; RHR#1 direction