| Radioactive Decay |
|
N = N 0 e - λt |
| Range of Projectile |
|
R = v 2 ⁢ sin ⁢ 2 θ g |
| Rectangle, Area of |
|
A = x ⁢ y |
| Reactance of a Capacitor |
|
X c = 1 ω ⁢ C |
| Reactance of an Inductor |
|
X L = ω ⁢ L |
| Refractive Index |
|
n = C C matter n = sin ⁢   i sin ⁢   r ⁢   ⁢ if ⁢   ⁢ the ⁢     other ⁢     refractive ⁢   ⁢ index = 1 |
| Refractive Index Related to Wave Velocities |
|
n = c v c m |
| Regular Polygon, Area of |
|
A = n ⁢ s ⁢ r 2 ⁢ ⁢         = p ⁢ r 2 |
| Relativistic Mass |
|
m = m 0 1 - v 2 c 2 |
| Relativistic Mass-Energy Relation |
|
E = m c 2 |
| Resolving Power (Rayleigh criterion) |
|
Δ ⁢ l = 1.22 ⁢ fλ D |
| Resonance Condition for I |
|
X L = X C |
| Resistivity |
|
E = ρ ⁢ J ρ = R ⁢ A l |
| Resistor in Parallel |
|
1 R = 1 R 1 + 1 R 2 + L ⁢       + 1 R n |
| Resistor in Series |
|
R = R 1 + R 2 + L ⁢           + R n |
| Rhombus, Area of |
|
A = x 1 x 2 2 |
| RMS speed of molecules in ideal gas |
|
c 2 ¯ = ( 3 R ⁢ T M ) 1 / 2 = ( 3 ⁢ p ρ ) 1 / 2 |
| Root Mean Square Current |
|
I r ⁢ m ⁢ s = I 0 / 2 |
| Root Mean Square Voltage |
|
V r ⁢ m ⁢ s = V 0 / 2 |
| Rotational kinetic energy |
|
T = 1 2 I ⁢ ω 2 |