Quantities (R)
radiance \(L\)radiant (energy) flux \(P\),\(\mathit{\Phi}\)radiant energy density \(\rho\),\(w\)radiant energy \(Q\)radiant exitance \(M\)radiant exposure \(H\)radiant intensity \(I\)radiant power \(P\)radiative lifetime \(\tau_{0}\)rate of conversion \(\dot{\xi}\)rate of fluid consumption \(q_{\text{V}}\)rate of reaction \(\nu\)reactance \(X\)reaction cross-section \(\sigma_{\text{r}}\)reduced mass \(\mu\)reflectance \(\rho\)refractive index \(n\)relative atomic mass \(A_\text{r}\)relative density \(d\)relative molecular mass \(M_{\text{r}}\)relative permeability \(\mu_{\text{r}}\)relative permittivity \(\varepsilon_{\text{r}}\)relative retardation \(R_{\text{rel}}\)relative retention \(r\)residence time \(t_{\text{r}}\)residual emission anisotropy resistance \(R\)resistivity \(\rho\)resolving power \(R\)response time \(\tau_{\text{R}}\)responsivity \(R\)retardation factor \(R\)retardation factor \(R_{\text{F}}\)retention factor \(k\)retention index \(I\)RM value \(R_{\text{M}}\)rotational correlation time \(\tau_{\text{c}}\),\(\theta\)rotational frequency \(f_{\text{rot}}\)rotational relaxation time \(\rho\)rotational term \(F\)