THE

ELECTRIC CHARGE

OF A PARTICLE

(LIKE A PARTICLE’S MASS)

IT IS A PROPERTY OF MATTER

SOME PARTICLES HAVE AN ELECTRIC CHARGE,

OTHERS DO NOT:

THE ELECTRON AND THE UP AND DOWN QUARKSARE EXAMPLES OF PARTICLES THAT

HAVE A CHARGE:

SOME PARTICLES HAVE AN ELECTRIC CHARGE,

OTHERS DO NOT:

UP QUARKCHARGE =

+⅔

ELECTRONCHARGE = -

1

DOWN QUARK

CHARGE = -⅓

SOME PARTICLES HAVE AN ELECTRIC CHARGE,

OTHERS DO NOT:

THE PHOTON AND THE NEUTRINO ARE EXAMPLES OF PARTICLES THAT

DO NOT HAVE A CHARGE:

PHOTON

CHARGE = 0

NEUTRINO

CHARGE = 0

THE PROTON HAS A NET CHARGE OF +1

DUE TOTHE QUARKS THAT MAKE IT UP

PROTON

CHARGE = +1

⅔ ⅔

⅓

THE NEUTRON HAS A NET CHARGE OF ZERO

DUE TOTHE QUARKS THAT MAKE IT UP

NEUTRON

CHARGE = 0

PROTON

CHARGE = +1

⅔ ⅔

⅓ ⅓

⅓⅔

THE PROTON HAS A NET CHARGE OF +1

DUE TOTHE QUARKS THAT MAKE IT UP

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

FOR EXAMPLE, YOU ARE PROBABLY AWARE THAT LIKE CHARGES

for example, two negative charges

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

FOR EXAMPLE, YOU ARE PROBABLY AWARE THAT LIKE CHARGES

for example, two negative charges

−− −−

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

FOR EXAMPLE, YOU ARE PROBABLY AWARE THAT LIKE CHARGES

for example, two negative charges

−− −−

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

FOR EXAMPLE, YOU ARE PROBABLY AWARE THAT LIKE CHARGES

for example, two negative charges

−− −−

will REPEL each other

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

AND THAT, OPPOSITE CHARGES

−−++

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

AND THAT, OPPOSITE CHARGES

--++

YOU ARE PROBABLY ALREADY FAMILIAR WITH SOME OF THE BEHAVIOURS OF CHARGED PARTICLES

AND THAT, OPPOSITE CHARGES

will ATTRACT each other

--++

A BEHAVIOUR OF CHARGED PARTICLES THAT YOU MAY NOT BE FAMILIAR WITH

IS WHAT HAPPENS TO THEM IN A MAGNETIC FIELD*

*The concept of FIELDS are useful in explaining so-called “action-at-a-distance” forces. For example, a gravitational field can be used to explain the attractive force of gravity, and an electric field can be used to explain the attraction of opposite charges and the repulsion of like charges. Likewise, magnetic fields can be used to explain why like poles of two magnets repel each other and their opposite poles attract.

You have probably seen how iron filings line themselves up

around a bar magnet:

We say that the iron filings align themselves with the magnetic field

that surrounds the magnet.

To show what happens to charged

particles in a magnetic field,

we take a “horseshoe”

magnet…

S

N

To show what happens to charged

particles in a magnetic field,

we take a “horseshoe”

magnet…

N

S

…and let this box outline the

region where the magnetic field is

concentrated.

N

S

The field has a direction associated with it, as

shown by the arrow. The direction of a magnetic field always points from

the North pole to the South pole of the magnet.

Dire

ction

of m

agne

tic fi

eld

N

S

If we were to send two

charged particles of equal mass into the

magnetic field…

Dire

ction

of m

agne

tic fi

eld

N

S

…one that is negatively charged…

Dire

ction

of m

agne

tic fi

eld

N

S

…and one that is positively charged…

Dire

ction

of m

agne

tic fi

eld

N

S

…we would find thatthe negatively

charged particle would be deflected

in this direction…

Dire

ction

of m

agne

tic fi

eld

N

S

Dire

ction

of m

agne

tic fi

eld

…we would find thatthe negatively

charged particle would be deflected

in this direction…

N

S

Dire

ction

of m

agne

tic fi

eld …and thatthe positively charged

particle would be deflected by

the same amount but

in the opposite direction.

N

S

…and thatthe positively charged

particle would be deflected by

the same amount but

in the opposite direction.

Dire

ction

of m

agne

tic fi

eld

N

S

…and thatthe positively charged

particle would be deflected by

the same amount but

in the opposite direction.

Dire

ction

of m

agne

tic fi

eld

(You should realize that using a magnet in this way could also be used to DETECT that two UNKNOWN particles had the SAME mass but OPPOSITE charge).