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An electron traveling toward the north with speed 4.0 × 105 m/s enters a region where the Earth’s magnetic field has the magnitude 5.0 × 10−
Question
An electron traveling toward the north with speed 4.0 × 105 m/s enters a region where the Earth’s magnetic field has the magnitude 5.0 × 10−5 T and is directed downward at 45° below horizontal. What is the magnitude of the force that the Earth’s magnetic field exerts on the electron? (e = 1.60 × 10−19 C)
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Physics
3 years
2021-07-22T15:27:54+00:00
2021-07-22T15:27:54+00:00 1 Answers
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Answer:
Explanation:
Speed of electron
v = 4 × 10^5 •j m/s
Magnetic field
B = 5 × 10^-5 T at angle of 45° to horizontal
Charge of electron
q = 1.6 × 10^-19C
Magnitude of force F?
The Force exerted in an electric field is given as
F = q(v×B)
Now, x component of the magnetic field
Bx = BCos45 = 5×10^-5 Cos45
Bx = 3.54 × 10^-5 •i T
Also, y component
By = BSin45 = 5 × 10^-5Sin45
By = 3.54 × 10^-5 •j T
B = 3.54 × 10^-5 •i + 3.54 × 10^-5 •j T
Now, F = q(v×B)
Note that,
i×i=j×j=k×k=0
i×j =k, j×k = i, k×i = j
j×i = -k, k×j = -i and i×k = -j
Therefore
F = q(v×B)
F = 1.6×10^-19(4×10^5•j × (3.54 × 10^-5 •i + 3.54 × 10^-5 •j T))
F = 1.6×10^-19 (4×10^5 × 3.54 × 10^-5 (j×i) + 4×10^5 × 3.54 × 10^-5(j×j))
F = 1.6×10^-19(14.14(-k) + 0)
F = —2.26 × 10^-18 •k N
It is in the negative direction of z axis
The magnitude of the force the field experience is 2.26 × 10^-18 N