Zusammenfassung der Ressource
Potential difference and electromotive force
- The volt
- 1V = 1JC^-1
- One volt is the p.d. across a component
when 1J of energy is transferred per unit
charge passing through the component
- Potential
difference is
measured in
volts
- Potential difference is
the energy transferred
from electrical energy to
other forms (heat,light,
etc.) per unit charge
- P.d. is used when charged
particles lose energy in a
component
- V = W / Q
- V is p.d. measured in volts
- W is the energy
transferred by
charge
- Q is charge in
couloumbs
- When work id done by the charge carriers
- The voltmeter
- A voltmeter is used to
measure p.d.
- It is connected in parallel
across a particular
component
- An ideal voltmeter has an
infinite resistance
- When connected, no
current passes
through the
voltmeter itself
- Electromotive force
- When work is done on
the charge carrier
- Charges are gaining energy as they
pass through a component
- The greater the e.m.f. the more
energy per coulomb has been
transferred into electrical energy
- Sources of e.m.f. include
solar cells, dynamos, and
thermocouples
- ε = W/Q
- Q is charge
in coulombs
- W is the energy
transferred
- ε is e.m.f.
measured in
volts
- E.m.f. is used when charged
particles gain energy from a
source
- The energy transferred from
chemical energy to electrical
energy per unit charge
- Calculating energy transfer
- W = VQ
- W = εQ
- The energy transferred from or
to the charges can be calculated
from the defining equations