Current Electricity formulas

Every formula JEE Advanced expects you to know for Current Electricity, with the variables spelled out. Free, no sign-up. Read it before a mock, not during one.

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Formulas: 32
Subject: Physics
Exam: JEE Advanced
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Current Electricity, every formula

32 formulas, typeset and free. Print it, or keep it open beside your practice.

Average current
$I_{a v} = \frac{Δ q}{Δ t}$
Instantaneous current
$I = \frac{d q}{d t}$
Current from drift velocity
$I = n e A v_{d}$
Drift velocity
$v_{d} = \frac{e E τ}{m}$
Mobility
$μ = \frac{v _{d}}{E} = \frac{e τ}{m}$
Current density
$J = \frac{I}{A} = σ E$
Resistance of a conductor
$R = \frac{ρl}{A}$
Resistivity
$ρ = \frac{m}{n e ^{2} τ} = \frac{1}{σ}$
Ohm's law
$V = I R$
Temperature dependence
$R = R_{0} (1 + α Δ T)$
Series combination
$R_{e q} = R_{1} + R_{2} + \dots$
Parallel combination
$\frac{1}{R _{e q}} = \frac{1}{R _{1}} + \frac{1}{R _{2}} + \dots$
Voltage division (series)
$V_{1} = \frac{R _{1}}{R _{1} + R _{2}} V$
Current division (parallel)
$I_{1} = \frac{R _{2}}{R _{1} + R _{2}} I$
Electric power
$P = V I = I^{2} R = \frac{V ^{2}}{R}$
Joule heating
$H = I^{2} R t$
Kirchhoff's junction rule
$\sum I_{in} = \sum I_{o u t}$
Kirchhoff's loop rule
$\sum I R + \sum ε = 0$
Wheatstone balance
$\frac{R _{1}}{R _{2}} = \frac{R _{3}}{R _{4}}$
Cells in series
$ε_{e q} = \sum ε_{i}, r_{e q} = \sum r_{i}$
Cells in parallel
$ε_{e q} = \frac{\sum ε _{i} / r _{i}}{\sum 1/ r _{i}}$
Terminal voltage (discharging)
$V = ε - I r$
Terminal voltage (charging)
$V = ε + I r$
Maximum power transfer
$R = r \Rightarrow P_{m a x} = \frac{ε ^{2}}{4 r}$
Ammeter shunt
$S = \frac{I _{g} R _{g}}{I - I _{g}}$
Voltmeter series resistance
$R_{s} = \frac{V}{I _{g}} - R_{g}$
Metre bridge
$X = (\frac{100 - l}{l}) R$
Potential gradient
$x = \frac{V}{L}$
Compare EMFs (potentiometer)
$\frac{ε _{1}}{ε _{2}} = \frac{l _{1}}{l _{2}}$
Internal resistance (potentiometer)
$r = (\frac{l _{1} - l _{2}}{l _{2}}) R$
Kilowatt-hour
$1 kWh = 3.6 \times 1 0^{6} J$
Cube across body diagonal
$R_{e q} = \frac{5 R}{6}$

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Current Electricity formulas

Current Electricity, every formula

Average current

Instantaneous current

Current from drift velocity

Drift velocity

Mobility

Current density

Resistance of a conductor

Resistivity

Ohm's law

Temperature dependence

Series combination

Parallel combination

Voltage division (series)

Current division (parallel)

Electric power

Joule heating

Kirchhoff's junction rule

Kirchhoff's loop rule

Wheatstone balance

Cells in series

Cells in parallel

Terminal voltage (discharging)

Terminal voltage (charging)

Maximum power transfer

Ammeter shunt

Voltmeter series resistance

Metre bridge

Potential gradient

Compare EMFs (potentiometer)

Internal resistance (potentiometer)

Kilowatt-hour

Cube across body diagonal

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