Electric Current Through Conductors — Class 11 Maharashtra HSC Physics revision notes
A 6-page visual revision sheet for Electric Current Through Conductors, written for Class 11 Maharashtra HSC Physics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDF
Electric Current Through Conductors in one look
drift speed, Ohm's law, resistors, resistivity, emf and Kirchhoff's rules
Current and drift speed
- current I = q/t for steady flow, or I = lim_Δ tto0Δ q/Δ t, unit ampere
- conventional current runs the way positive charge would move, opposite to electron flow in a metal
- no field: free electrons move randomly at sim10^6 m s^-1, no net drift
- field applied: electrons drift opposite E at only 10^-4 to 10^-5 m s^-1, ten orders slower
Current, drift speed and current density
- charge in a length L, n electrons per unit volume
q = nALe - current in terms of drift speed
I = nAv_de - current density
J = I/A = nev_d
Q. A wire of diameter 0.02 m has 10^28 free electrons per m^3 and carries 100 A. Find the drift speed.
- A = π r^2 = π(0.01)^2 = 3.14×10^-4 m^2
- v_d = I/nAe = 100/10^28×3.14×10^-4×1.6×10^-19
- denominator = 10^28×3.14×10^-4×1.6×10^-19 ≈ 5.02×10^5
Answer: v_d ≈ 1.99×10^-4 m s^-1
Ohm's law
- statement, physical state unchanged
I ∝ V - resistance
V = IR, R = V/I - conductance
C = 1/R
Page 1 of 6. The full sheet, all 6 pages, opens free in the app.
What this Electric Current Through Conductors sheet covers
- electric current
- drift speed
- Current and drift speed
- Current, drift speed and current density
- charge in a length L, n electrons per unit volume
- current in terms of drift speed
- current density
- ohm's law
- statement, physical state unchanged
- resistance
- conductance
- Ohm's law, the microscopic picture
- Electrical energy and power
- work to move charge Q through p.d. V
- power delivered
- power dissipated in a resistor, using Ohm's law
- Resistors and colour code
- Series and parallel combination
- series, same current in each
- parallel, same voltage across each
- resistivity
- specific resistance
- resistance of a uniform conductor
- conductivity
- field-current density form
- Resistivity and resistance: the limits
- Resistance and temperature
- linear approximation
- temperature coefficient of resistance
- emf
- internal resistance
- EMF and internal resistance
- Cell in a circuit
- terminal voltage under load
- current drawn, external resistance R
- maximum possible current, R = 0
- Cells in series vs parallel
- Series
- Parallel
- kirchhoff's laws
- junction rule
- loop rule
- The two rules, written out
- junction rule, at any node
- loop rule, around any closed loop
- wheatstone bridge
- balanced bridge
- Balance condition
- balanced bridge, no current through the galvanometer
- Unknown resistance from a balanced bridge
- Symbols
- Traps that cost marks
- Tricks that save time
How CapCompass uses this sheet
These notes are not a standalone PDF. CapCompass plans Physics chapter by chapter against your real exam dates and free hours, and when the plan reaches Electric Current Through Conductors the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.