Excitation & ionisation

Electrons in a fluorescent tube are accelerated from rest by a potential difference of 130 V.

Calculate the maximum speed of an electron that is accelerated from rest by this potential difference.

Explain why the average speed of the electrons in the tube is much less than the maximum speed you calculated in Question 08.1.

Scientists want to replace the mercury in fluorescent tubes with substance X.

Figure 12 is an emission spectrum for X.

White light consists of the whole range of visible wavelengths from 380 nm to 700 nm

Explain, with reference to Figure 12, whether white light can be produced by a fluorescent tube that uses X.

Figure 12 shows a maximum intensity peak that occurs at wavelength λ_peak.

Calculate, in eV, the energy change of an atom that produces a photon with a

The diagram shows some of the energy levels for a hydrogen atom.

Photons of energy 12.74 eV excite hydrogen atoms that are all initially in the ground state (n = 1).

How many different photon frequencies are emitted as the atoms return to their

Photoelectrons are released when monochromatic light with a photon energy of 4.2 × 10⁻¹⁹ J is incident on a metal surface. The work function of the surface is 2.4 eV.

What is the maximum speed of the photoelectrons as they leave the surface?

A fluorescent tube contains a gas.

The coating of the tube

What is the role of the mercury vapour in a fluorescent tube?

A photon has energy of 1 × 10¹⁸ eV. An object of mass 0.03 kg has kinetic energy equal to the energy of the photon.

What is the speed of the object?

An electron collides with an isolated atom and raises an atomic electron to a higher energy level.

Which statement is correct?

An electron collides with an isolated atom and raises an orbiting electron to a higher energy level.

Which statement is correct?

Charged plates X and Y have a potential difference 1.5 V between them.

Which particle gains 3.0 eV of kinetic energy when moving from Y to X ?

Table 1 shows results of an experiment to investigate how the de Broglie

Calculate a value for the Planck constant suggested by the data in Table 1.

Figure 2 shows the side view of an electron diffraction tube used to demonstrate the wave properties of an electron.

An electron beam is incident on a thin graphite target that behaves like the slits in a diffraction grating experiment. After passing through the graphite target the electrons strike a fluorescent screen.

Figure 3 shows the appearance of the fluorescent screen when the electrons are incident on it.

Explain how the pattern produced on the screen supports the idea that the electron beam is behaving as a wave rather than as a stream of particles.

Explain how the emission of light from the fluorescent screen shows that the electrons incident on it are behaving as particles.

The diagram shows an energy - level diagram for a hydrogen atom.

Electrons, each having a kinetic energy of 2.0 × 10⁻¹⁸ J, collide with atoms of hydrogen in their ground state. Photons are emitted when the atoms de-excite.

How many different wavelengths can be observed with incident electrons of this energy?

Photons of wavelength 290 nm are incident on a metal plate. The work function of the metal is 4.1 eV

What is the maximum kinetic energy of the emitted electrons?

Electrons with energy 13.0 eV collide with atoms of hydrogen in their ground state.

What is the number of different wavelengths of electromagnetic radiation that could be emitted when the atoms de-excite?