COMEDK · Physics · 17. Electrostatics
An electric field and magnetic field \(1.8 \times 10^4\ Vm^{-1}\) and \(6 \times 10^{-3}\ T\) respectively are applied simultaneously on an electron beam such that path of the beam remains undeviated, then the speed of the electron will be:
- A \(3 \times 10^6\ ms^{-1}\)
- B \(3 \times 10^7\ ms^{-1}\)
- C \(1.5 \times 10^6\ ms^{-1}\)
- D \(1.5 \times 10^7\ ms^{-1}\)
Answer & Solution
Correct Answer
(A) \(3 \times 10^6\ ms^{-1}\)
Step-by-step Solution
Detailed explanation
For an electron beam to remain undeviated in the presence of crossed electric and magnetic fields, the net force on the electrons must be zero. \(F_e = F_m\) \(qE = qvB\) \(v = \dfrac{E}{B}\) Substituting the given values: \(v = \dfrac{1.8 \times 10^4}{6 \times 10^{-3}}\)…
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