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प्रश्न
Write the expression for the Lorentz force on a particle of charge q moving with a velocity `vecv` in a magnetic field `vecB`. When is the magnitude of this force maximum? Show that no work is done by this force on the particle during its motion from point `vecr_1` to point `vecr_2`.
उत्तर
Lorentz force = Magnetic force + Electric force
⇒ `vecF = q(vecv xx vecB)`
`vecF = q.v.B sintheta`
when θ = 90° the Lorentz force is maximum.
If `vec(ds)` is the instantaneous displacement of charge and `vec(ds)` is also perpendicular to `vecF`.
Then,
W = `vecF. vec(ds)`
= `vecF vecs costheta`
= F.s cos90°
cos90° = 0
So, W = 0
Hence, no work is done by this force on the particle during its motion from a point `vecr_1` to point `vecr_2`.
संबंधित प्रश्न
Seema’s uncle was advised by his doctor to have an MRI (Magnetic Resonance Imaging) scan of his brain. Her uncle felt it to be expensive and wanted to postpone it. When Seema learnt about this, she took the help of her family and also approached the doctor, who also offered a substantial discount. She then convinced her uncle to undergo the test to enable the doctor to know the condition of his brain. The information thus obtained greatly helped the doctor to treat him properly.
Based on the above paragraph, answer the following questions:
(a) What according to you are the values displayed by Seema, her family and the doctor?
(b) What could be the possible reason for MRI test to be so expensive?
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