Question

3. Based on your observation of the electron beam, what characteristic of the beam assures us that the electrons all have the same mass? Note: This characteristic forms the basis for a mass spectrometer. 4. Explain on the basis of their own created magnetic fields why a group of electrons all moving in the same direction stays together Further Investigation 1. 12 points) Locate the controls and connections for lower voltage power supply (0 - 50 VDC) contained in the box

need help with question 3-4

Answer 1

3). As the electron beam enters the magnetic field it faces the turning force and starts moving in a circular path with radius

$R=\frac{mv}{Bq}$

Clearly the radius for the particles depends on the mass and velocity of the particles. As the particles in a beam have the same radius of curvature. It implies that they have the same mass, same velocity and same charge.

4). If we see the individual electrons as the current in an infinite long wire. Then we realise that as the parallel current carrying wires have the attractive force between them if the direction of current is same( due to force generated by the induced magnetic field by one wire on other). These electrons will also have the attractive force between them because they move in same direction and hence they stay in a group.