Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

Theme B — The Particulate Nature of Matter

B.5.10 Sources of Electrical Energy — IB Physics HL Revision Notes & Topical Questions

5 min read 10 parts Lesson 51 of 53 1 quiz

📚 IB Physics HL Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
0%read
Lesson summary

B.5.10 Sources of Electrical Energy — IB PHYSICS SL notes: Describe how cells, batteries, solar cells and other sources supply electrical energy and compare their advantages and disadvantages.Energy conversion — a source transforms energy from another form into electrical potenti…

  • Primary cell
  • Secondary cell
  • Solar (photovoltaic) cell
  • Energy available
  • Energy density
  • Non-rechargeable cells

Section 1 of 10What a source does

Energy conversion
  • Energy conversion a source transforms energy from another form into electrical potential energy for the charge in a circuit
  • A chemical cell converts chemical energy.
  • A solar cell converts light energy.
  • A generator converts kinetic energy.
  • A thermocouple converts thermal energy.
E.m.f.
  • E.m.f. the source gives each coulomb a fixed amount of energy (B.5.11)
  • It maintains the p.d. between its terminals by continuous conversion of energy.
Forms
  • Forms chemical cells, solar cells, wind generators and mains electricity are common sources

Section 2 of 10Primary and secondary cells

Primary cell
  • Primary cell its chemicals react irreversibly, so it cannot be recharged once the reactants are used up
  • Zinc–carbon and alkaline cells have an e.m.f. near 1.5 V.
Secondary cell
  • Secondary cell it uses a reversible chemical reaction, so it can be recharged and reused many times
  • A charger forces current backwards through the cell and restores the chemicals.
  • Lithium-ion cells (about 3.7 V) are used in laptops and phones.
  • Lead–acid cells (about 2.0 V per cell, 12 V for six) are used in vehicles.
Battery
  • Battery a group of cells joined in series to give a higher e.m.f.

Section 3 of 10Charging and discharging

Discharge
  • Discharge the secondary cell acts as a source and chemical energy is converted to electrical energy
Charge
  • Charge an external supply of larger p.d. forces current in the reverse direction, converting electrical energy back to chemical energy
Losses
  • Losses the process is never fully efficient
  • Some energy appears as thermal energy in the internal resistance.
  • A charge and discharge cycle returns typically 85–95% of the stored energy for lithium-ion cells.

Section 4 of 10Solar and fuel cells

1Solar (photovoltaic) cell
  • Solar (photovoltaic) cell a semiconductor junction in which photons of enough energy free electrons
  • The electrons move through the external circuit and transfer energy there.
  • The output depends on the incident intensity and area, since power received = intensity × area.
  • Typical efficiency is 15–22%.
2Fuel cell
  • Fuel cell it converts the chemical energy of a fuel, commonly hydrogen, and oxygen directly into electrical energy
  • Water is the only product.
  • It does not run down while fuel is supplied continuously.
  • Its efficiency is about 40–60%, but it needs a hydrogen source.

Section 5 of 10Capacity and stored energy

Capacity
  • Capacity the charge a cell can deliver before it is exhausted, usually in A h or mA h
  • 1 A h = 3600 C and 1 mA h = 3.6 C.
Energy available
  • Energy available roughly E = qV, the capacity in coulombs multiplied by the e.m.f.
Energy density
  • Energy density the energy stored per unit mass, in J kg−1
  • Lithium-ion cells reach about 0.9 MJ kg−1, around three times that of lead–acid cells.
  • They are chosen where weight matters.

Section 6 of 10Comparing sources

SourceAdvantagesDisadvantages
Single-use battery (alkaline)Portable, low cost, convenient, high energy density, many can join in series for greater p.d.Non-rechargeable, limited power, high internal resistance, disposal pollution, non-renewable materials
Lithium-ion batteryVery high energy density, high efficiency, rechargeable, long lifetime, fast charging, low internal resistanceExpensive, capacity degrades over time, internal resistance rises over time
Lead–acid batteryLow cost, rechargeable, delivers very high currents quicklyHeavy for its power, internal resistance rises as it degrades, limited full discharge cycles, toxic and corrosive materials
Solar cellUnlimited free energy, clean, no fuel, cheap maintenanceVariable output, daytime only, limited efficiency, large areas and high upfront cost
Wind generatorNo fuel cost, no chemical pollution, sustainableInconsistent output, needs windy sites, noise and visual pollution, high set-up cost
Fossil-fuel power stationExisting infrastructure, high energy density fuel, reliable at any time, developed technologyProduces greenhouse gases and pollution, non-renewable

Section 7 of 10Choosing a source

Factors
  • Factors e.m.f., maximum current, capacity, mass, cost, rechargeability and environmental effect
    • (low internal resistance)
Non-rechargeable cells
  • Non-rechargeable cells cheap with a long shelf life, so they suit low-power devices such as clocks
Rechargeable cells
  • Rechargeable cells they suit heavy use
Solar cells
  • Solar cells they supply nothing at night, so they must be paired with a store
Power stations
  • Power stations conventional stations generate current by electromagnetic induction, driven by steam or flowing water

Section 8 of 10More from the specification

More from the specification
Combined resistance
  • Single resistance that could replace several resistors.
Circuit diagram
  • Drawing of a circuit using standard symbols.
Parallel
  • Components on separate branches, each with the full e.m.f.
Component
  • Part of a vector along one axis.
Resistivity
  • Property of a material defined by ρ = RA/L.
Thermistor
  • Resistor whose resistance falls as temperature rises.
Components
  • Perpendicular parts of a vector that add to give the vector.
Ammeter
  • Component that measures current.
Temperature
  • Measure of the average kinetic energy of the particles.
Voltmeter
  • Instrument that measures p.d., connected in parallel.
Lost volts
  • Lost volts the potential difference used up across a cell's internal resistance, which is a fixed property of the cell.

Section 9 of 10Key terms

TermMeaning
Primary cellCell that cannot be recharged because its reaction is not reversible.
Secondary cellRechargeable cell using a reversible chemical reaction.
Fuel cellCell that continuously converts the energy of a fuel and oxygen into electricity.
Photovoltaic cellSemiconductor device converting light into electrical energy.
CapacityCharge a cell can supply, in A h or C.
Energy densityStored energy per unit mass or volume.

Section 10 of 10Exam technique

1
Saying a battery stores charge — it stores chemical energy; the charge is already in the circuit.
2
Calling a single cell a battery.
3
Adding the e.m.f.s of cells connected in parallel — in parallel the e.m.f. stays the same.
4
Forgetting to convert mA h to coulombs by multiplying by 3.6.
5
Thinking a solar cell works equally well in all light — its output depends on the intensity.

Last updated:

\n