Toby

Question 1

Explain why a charge moving in a magnetic field experiences a force

Answer 1

A moving charge will create its own magnetic field and when this is placed in another magnetic field a force will be placed on the moving charge.

Question 2

Explain why a charge travelling in magnetic field travels in a circular motion

Answer 2

magnetic fields exert forces on particles perpendicular to their velocity, this results in the particle travelling in a circular motion due to a constant acceleration towards the centre.

Question 3

Briefly describe how Thomson measured charge-to-mass ration of cathode rays

Answer 3

Thomson set up the cathode ray device with a magnetic and electric field which would oppose the others force. By adjasting these to fields to cancel each other out, Thomson calculated the velocity and radius of particles motion. these figures allowed thomson to determine the charge-to-mass ratio for cathode rays.

Question 4

explain the significance of the charge-to-mass ratio of cathode rays.

Answer 4

charge to mass ratio allowed for the following conclusions to be made

• cathode rays were a particle and not a wave
• they had a mass smaller than anything seen before
• led to discovery of electrons