Start of Class: Structure of the atom

After DC voltage was applied to an apparatus containing hydrogen gas, the hydrogen separated into streams of oppositely charged particles. What could be concluded from this observation?

• Hydrogen gas conducts electricity.

• Hydrogen is the simplest element.

• Hydrogen atoms have components.

• Hydrogen atoms have a neutral charge.

Which of the following is true in relation to Millikan’s oil drop experiment?

• Measure the charge-to-mass ratio of electrons - Electric and magnetic

• Measure the charge-to-mass ratio of electrons - Magnetic

• Measure the charge of electrons - Electric and magnetic

• Measure the charge of electrons - Electric

In an experiment, an electrically charged oil drop was suspended in air by an electric field. The electric field could be adjusted to balance the weight of the oil drop. If more drops were suspended and measurements taken, which of the following properties would all of the oil drops be observed to have in common?

• The mass of each drop would be a multiple of a fundamental mass.

• The mass of each drop would be the same as each of the other drops.

• The charge of each drop would be a multiple of a fundamental charge.

• The charge of each drop would be the same as each of the other drops.

What does the Maltese cross apparatus demonstrate about cathode rays?

• They travel in straight lines.

• They consist of a beam of electrons.

• They are absorbed by a metal surface.

• They are not affected by magnetic fields.

Which diagram correctly shows the deflection of a cathode ray by a bar magnet?

• (A)

• (B)

• (C)

• (D)

The diagram shows a type of cathode ray tube. Which of the following statements cannot be inferred from observations made.

• Cathode rays possess energy.

• Cathode rays possess momentum.

• Cathode rays travel in straight lines.

• Cathode rays cannot pass through metals.

The diagram shows a cathode ray entering a magnetic field. An electric field is applied to cancel the effect of the magnetic field on the cathode ray. Which row of the table correctly describes the direction of the applied electric field, and the direction of the force acting on the cathode ray as a result of the magnetic field?

• ↑, ↑

• ↓, ↑

• ↑, ↓

• ↓, ↓

An electron is projected at 90° into a magnetic field of 9 × 10⁻⁴ T, at a speed of 1 × 10⁷ m s⁻¹. This causes the electron to undergo uniform circular motion. Calculate the radius of the electron’s path. (3 d.p. no unit)

Mathematical Equivalence

ON

Answer explanation

A cathode ray beam strikes the screen at point P, producing a bright spot. The north end of a magnet is brought towards the beam as shown. Towards which point does the bright spot move?

• A

• B

• C

• D

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

• perpendicular magnetic fields.

• perpendicular electric fields.

• parallel electric and magnetic fields.

• perpendicular electric and magnetic fields.