Question
sics 108, Fall 2017-Midterm #2 5) 120 points] In a mass spectrometer, a beam of hydrogen ions (charge ote 1.00 × 10° m/s emerge from the velocity selector with electric and magne perpendicular to the ion velocity +le) with speed of fields mutually a. If the magnetic field in the velocity selector has a magnitude of 0.010 magnitude of the electric field for the ions to emerge with 10-19C, mr= 1.67x10-27 kg) being deflected? (e-1.60- b. After passing through the velocity selector the ions encounter a perpendicular magnetic o move in a circular path. Calculate the radius of field of 0.050T that causes the beam t the circular path. c. [10 points] A 100 Watt light bulb is connected to a standard 120V household circuit. a. How much current does the light bulb draw? b. What is the maximum number of 100 Watt bulbs that can be connected in parallel before tripping a 15.0A circuit breaker?
Explanation / Answer
5) a) E = vB = 105 x 0.01 N/C = 1000 N/C
b) R = mv/qB = (1.67 x 10-27 x 105)/(1.60 x 10-19 x 0.05) = 0.020875 m = 2.0875 cm
c) a) I = P/V = 100/120 = 0.83333 A
b) 15 = P/120 => P = 1800 W
number of bulbs = 1800/100 = 18 bulbs
