levo

Wave Properties

Wavelength, slit width and the spread of the beam

  • 3 things to know
  • Component 3

Overview

Recall questions on diffraction depending on the ratio of wavelength to slit width, the condition for roughly semicircular spreading, the condition for a beam spreading through less than 180 degrees, and why a small loudspeaker spreads high notes more widely.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

Explain why diffraction of light became observable once very narrow slits could be made.

Key term

State the condition for there to be very little diffraction at a slit.

Key term

Describe the wavefronts beyond a slit whose width is equal to or less than the wavelength.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    On what does the amount of diffraction at a slit depend?

    Model answer

    On the ratio of the wavelength to the width of the slit.

  2. 2

    State the condition for there to be very little diffraction at a slit.

    Model answer

    The wavelength must be much smaller than the width of the slit.

  3. 3

    Describe the wavefronts beyond a slit whose width is equal to or less than the wavelength.

    Model answer

    The waves spread as roughly semicircular wavefronts, filling the whole region beyond the slit.

  4. 4

    Describe the beam beyond a slit whose width is greater than the wavelength.

    Model answer

    The main beam spreads through less than 180 degrees, so a distinct forward beam remains with the spreading confined to its edges.

  5. 5

    What happens to the spread of the beam as the slit is narrowed at fixed wavelength?

    Model answer

    The beam spreads through a larger angle.

  6. 6

    A wave of twice the wavelength passes through the same slit. How does its spread compare?

    Model answer

    It spreads through a larger angle, because the ratio of wavelength to slit width has doubled.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Basic Physics
Kinematics
Dynamics
Energy Concepts

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

The wires .
attractrepeltwist

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe equation is pV = NkT.
BThe pressure, p, is in Pa.
CThe volume V is in m³.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

The joule is a unit of energy.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Wave Properties, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.