JEE Main201911 Jan 2019Morning ShiftPhysicsMagnetic Effects of CurrentActual
In an experiment, electrons are accelerated, from rest, by applying a voltage of 500 ~V . Calculate the radius of the path if a magnetic field 100 mT is then applied. [Charge of the electron =1.6 10⁻¹⁹ C Mass of the electron .=9.1 10⁻³¹ ~kg ]
Options
- A7.5 10⁻³ ~m
- B7.5 10⁻² ~m
- C7.5 ~m
- D7.5 10⁻⁴ ~m
Correct answer
D. 7.5 10⁻⁴ ~m
Step-by-step solution
Radius of the path (r) is given by r = mv qB aligned r &= 2 mk eB ( p = mv = 2 mk ) &= 2 meV eB ( k = eV ) r &= 2 ~m e V B = 2 9.1 10⁻³¹ 1.6 10⁻¹⁹ (500) 100 10⁻³ aligned r= 9.1 0.16 10⁻¹⁰ 10⁻¹ = 3 4 10⁻⁴=7.5 10⁻⁴