An electron is moving at 7.4x105 m/s perpendicular to a magnetic field. It experiences a force of 2.0x10–13 N. What is the magnetic field strength?

1.69 T

Explanation:

Applying,

F = BvqsinФ Equation 1

Where F = Force, B = magnetic field, v = velocity, q = charge on an electron, Ф = angle between the electron and the field.

make B the subject of the equation,

B = F/(vqsinФ) Equation 2

From the question,

Given: F = 2.0×10⁻¹³ N, v = 7.4×10⁵ m/s, Ф = 90°

Constant: q = 1.60×10⁻¹⁹ C

Substitute into equation 2

B =  2.0×10⁻¹³/(7.4×10⁵×1.60×10⁻¹⁹×sin90°)

B = 0.169×10

B = 1.69 T

the correct answer is b

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