op-amp circuit explanation
You're first picture has no component called \$R_c\$, but we can clearly see that \$V_o = I_c R_c\$ does not apply for the second picture, but instead it is 
$$V_{R_c} = I_c R_c \qquad V_o = V_{cc} - I_c R_c$$

But when doing a AC-Analysis \$V_{cc}\$ is removed, as it is a constant voltage source, and therefor \$R_c\$ is short-circuited to ground. Then you actually have \$V_o = I_c R_c\$.

Attention: AC-Analysis vs. DC-Analysis

We use DC-Analysis to find the bias-/working-point. With the small-signal-model we can use, altough being restricted to a bounded input voltage, a linear model for easier analysis of the circuit, despite the nonlinear behavior of a transistor.

Microelectronic circuits from Sedra&amp;Smith is a very good source of information if you're new to electronics.