levo

Probing Deep Into Matter

Quarks, hadrons and leptons

  • 3 things to know
  • Components 01, 02 and 03

Overview

Recall questions on the quark compositions and charges of protons, neutrons and antiprotons, the charges of up and down quarks, hadrons, leptons and gluons, antiparticles and the positron, lepton numbers, neutrinos and why they are hard to detect, why free quarks are never seen, and beta-minus decay at quark level.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

State the quark composition of a proton.

Key term

State the quark composition of a neutron.

Key term

State the charges of the up quark and the down quark.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    State the quark composition of a proton.

    Model answer

    A proton is made of two up quarks and one down quark.

  2. 2

    State the quark composition of a neutron.

    Model answer

    A neutron is made of one up quark and two down quarks.

  3. 3

    State the charges of the up quark and the down quark.

    Model answer

    The up quark carries +2/3 of the elementary charge and the down quark carries −1/3 of it.

  4. 4

    Show that the quark composition of a proton gives it a charge of +1e.

    Model answer

    Two up quarks and one down quark give +2/3 + 2/3 − 1/3, which is +1 in units of the elementary charge.

  5. 5

    Show that the quark composition of a neutron gives it zero charge.

    Model answer

    One up quark and two down quarks give +2/3 − 1/3 − 1/3, which is zero.

  6. 6

    What is a hadron?

    Model answer

    A hadron is a particle built from quarks that feels the strong interaction, and protons and neutrons are the familiar examples.

Other ways to work this

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The two charges .
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Blank Blitz makes facts automatic

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

AThe neutron has lepton number 0.
BOn the other side the proton has 0.
CThe electron has +1 and the antineutrino has −1.

Build It gets the exam shape right

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

There are 2π rad in a full circle.
TrueFalse

Test It catches misconceptions

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

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Brain Breaks between sessions

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

Every question in Probing Deep Into Matter, 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.

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