Summary OCR A level Physics A 4.2 Energy, power and resistance
18 views 0 purchase
Course
Module 4: Electrons, waves and photons
Institution
OCR
Summary notes for topic 4.2 Energy, power and resistance covering potential difference, electromotive force, resistance, circuit symbols, the electron gun, Ohm’s law, I-V characteristics, resistivity, thermistors, LDRs, power and paying for electricity . Notes include definitions, highlighted key...
Used to described when work is done
by charge carriers .
When electrical
energy is converted into other forms of
the
energy by in the
charge
circuit
carriers when
they lose
energy
to the
components .
Measured in volts .
One volt describes
joule of energy one
transferred per unit charge passing through the component
IV = IJC "
V V,
Wg
in volts V
potential difference
=
, ,
energy transferred joules J
W, ,
in ,
Q in coulombs C
,
charge , ,
Voltmeters are used to measure pd .
and are
always
connected in parallel across a
particular component .
An ideal voltmeter should have an infinite resistance so that
no current passes through it when connected .
, Electromotive force .
Used to describe when work charge carriers is done on the .
The
energy gained by the charge carriers they pass as
through a cell or
battery
to electrical
converted
as other
forms of energy ,
are
energy
.
The
energy transferred from chemical
energy for other)
to electrical unit
energy per charge
.
E
¥ E mf in volts V
=
e.
, , ,
J
energy transferred in joules
w, ,
Q, charge in coulombs C
, ,
.
The electron
gun
Metal filament heated by electric
•
current .
•
Electrons in filament gain kinetic
energy .
•
Meaning some escape from the metal .
•
thermionic emission emission of electrons -
through the action of
heat .
Vacuum + high p.cl filament
between anode make
filament
•
.
+
act like a cathode .
•
Electrons accelerate towards anode -
Electrons
gain kinetic energy
• .
•
If anode has a small hole electrons in line , pass through creating
,
a beam of electrons with specific kinetic
energy
.
Work done electron in kinetic
on an
gain energy
=
eV 1-2 my
2
=
elementary charge 11.6×10 a) in coulombs, C
'
e.
_
,
V,
accelerating p d. in volts V
.
, ,
M Mass . of an electron , in kilograms kg ,
*
' *
take
velocity , in metres per second Ms average speed
-
> an
V, ,
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller hannahgrason. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $9.08. You're not tied to anything after your purchase.
