An electron enters a magnetic field at right angle to it. In which direction will the electron move? State the principle applied by you in finding the direction of electron.
Answers
Explanation:
electron enters a uniform magnetic field at right angles.
The electron will move normally outward.
Magnetic fields
The force (F) on wire of length L carrying a current I in a magnetic field of strength B is given by the equation:
F = BIL
But Q = It and since Q = e for an electron and v = L/t you can show that :
Magnetic force on an electron = BIL = B[e/t][vt] = Bev where v is the electron velocity
In a magnetic field the force is always at right angles to the motion of the electron (Fleming's left hand rule) and so the resulting path of the electron is circular (Figure 1).
Therefore :
Magnetic force = Bev = mv2/r = centripetal force
v = [Ber]/m
and so you can see from these equations that as the electron slows down the radius of its orbit decreases.
Charged particles move in circles at a constant speed if projected into a magnetic field at right angles to the field.
Charged particles move in straight lines at a constant speed if projected into a magnetic field along the direction of the field.
electron moving at right angles to a uniform magnetic field.
If the electron enters the field at an angle to the field direction the resulting path of the electron (or indeed any charged particle) will be helical as shown in figure 3. Such motion occurs above the poles of the Earth where charges particles from the Sun spiral through the Earth's field to produce the aurorae.
