The Discovery of the Electron by J.J. Thomson

JJ Thomson determined the charge/mass ratio of the electron by constructing a device which contained

• perpendicular magnetic fields.

• perpendicular electric and magnetic fields.

• perpendicular electric fields.

• parallel electric and magnetic fields.

Answer explanation

In order to generate forces in opposition the electric field needs to be perpendicular to the magnetic field.

What did Crooks believe about the particles in the cathode ray tube?

• They were a form of electromagnetic radiation.

• They were positively charged.

• They were negatively charged particles.

• They were a form of light.

Answer explanation

Crooks believed that the particles in the cathode ray tube were negatively charged particles.

What was J.J. Thomson able to determine by applying both electric and magnetic fields to the cathode ray?

• The speed of light

• The exact charge of the electron

• The exact mass of the electron

• The charge to mass ratio of the electron

Answer explanation

By applying both electric and magnetic fields to the cathode ray, J.J. Thomson was able to determine the charge to mass ratio of the electron.

What did J.J. Thomson's experiments conclude about the nature of cathode rays?

• They could not be deflected by electric or magnetic fields.

• They were made up of negatively charged particles, electrons.

• They were made up of positively charged particles.

• They were a form of electromagnetic radiation.

Answer explanation

Thomson's experiments concluded that cathode rays were made up of negatively charged particles, electrons.

What significant discovery did J.J. Thomson make regarding the cathode ray particle compared to the hydrogen atom?

• It was 1800 times smaller.

• It was the same size.

• It had the same charge to mass ratio.

• It was 1800 times larger.

Answer explanation

J.J. Thomson discovered that the cathode ray particle was 1800 times smaller than the hydrogen atom, highlighting the correct choice.