Turning points quiz

Who discovered that gases at sufficiently low pressure in sealed glass tubes conduct electricity and glow with light of a characteristic color?

• J.J. Thomson

• Ernest Rutherford

• Niels Bohr

• William Crookes

What observation did William Crookes make about the glowing gas in a discharge tube?

• The glowing gas near the anode is called the positive column

• The glowing gas near the cathode is called the negative glow

• The glowing gas near the anode is called the negative column

• The glowing gas near the cathode is called the positive glow

What did the 'paddle wheel' experiment demonstrate about cathode rays?

• Cathode rays have no mass and no charge

• Cathode rays are positively charged particles

• Cathode rays are capable of moving through a gas and causing a paddle wheel to rotate

• Cathode rays are unaffected by magnets

What did Joseph J Thomson prove about cathode rays?

• Cathode rays are made up of protons

• Cathode rays are made up of neutrons

• Cathode rays are made up of positively charged particles

• Cathode rays are made up of negatively charged particles

What causes the emission of light from a discharge tube?

• The high voltage applied to the tube ionises some of the gas atoms

• The low voltage applied to the tube ionises some of the gas atoms

• The neutral atoms in the tube emit light without any voltage

• The cathode rays emit light when they hit the anode

What is the 'negative glow' in a discharge tube due to?

• Electrons emitted from the cathode surface

• Photons emitted when some of the positive ions and electrons recombine

• The reflection of light from the anode

• The absorption of light by the cathode

What term was used to describe electrons that are attracted to the anode and move away from the cathode in a discharge tube?

• Anode rays

• Cathode rays

• Excitation rays

• Conduction rays

What causes the positive column of glowing gas in a discharge tube?

• De-excitation of excited gas atoms

• Recombination of electrons with gas atoms

• Emission of photons of visible light

• Collision of electrons with the anode

What is thermionic emission?

• The emission of electrons when a gas is heated

• The emission of electrons when a metal is heated

• The emission of photons from a metal surface

• The emission of electrons due to a high voltage

What is the role of the anode in thermionic emission?

• It emits electrons when heated

• It accelerates the electrons to form a narrow beam

• It recombines with the electrons

• It provides the kinetic energy to the electrons