1. An electron travels with a speed of 2.58 x 10 6 m/s at an angle of 39.8° with
ID: 1431518 • Letter: 1
Question
1. An electron travels with a speed of 2.58 x 106 m/s at an angle of 39.8° with respect to a 0.931 T magnetic field. What is the magnitude of the magnetic force on the electron?
A) 2.42 x 10-13 N
B) 2.44 x 10-13 N
C) 2.46 x 10-13 N
D) 2.48 x 10-13 N
E) None of these
2. A current of 9.45 mA is maintained in a single circular loop with a diameter of 1.53 m. A 645 mT magnetic field is directed parallel to the plane of the loop. Determine the magnitude of the torque exerted by the magnetic field on the loop.
A) 11.2 mN×m
B) 11.4 mN×m
C) 11.6 mN×m
D) 11.8 mN×m
E) None of these
3. When a 6.54 resistor is connected to a battery that has a 0.240 internal resistance, the potential drop across the terminals of the battery is 9.00 V. What is the emf of the battery?
A) 9.31 V
B) 9.33 V
C) 9.35 V
D) 9.37 V
E) None of these
More detailed explanations would be helpful for me!
Explanation / Answer
1.
mag field B = 0.931 T
v = 2.58 x 10^6 m/s
theta = 39.8
q = 1.6 x 10^-19 C
Force = Bqv sin theta = 0.931 x 1.6 x 10^-19 x 2.58 x 10^6 sin 39.8 = 2.46 x 10^-13 N (option C)
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2. torque on loop = B sin theta = (9.45 x 10^-3 x pi x (0.765)^2 ) 0.645 (1) = 11.2 mNxm option A
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3. R = 6.54 ohmsV
battery resistance, r =0.24 ohms
V = 9 volts
battery emf = e
current drawn i = 9/6.54 = 1.38 A
e = V + i (r) = 9 + 1.38 (0.24 ) = 9.33 v option B
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