update image caption

_posts/2024-03-10-where-does-energy-go.md

@@ -157,6 +157,7 @@ trillions of parameters!
 ## Computer system
 
 ![A Von-Neumann computer architecture.](https://yueguoguo.github.io/images/vn_architecture.png) 
+<font size="1">A Von-Neumann computer architecture.</font>
 
 The contemporary computer system follows the [Von-Neumann
 structure](https://en.wikipedia.org/wiki/Von_Neumann_architecture) (probably
@@ -248,12 +249,13 @@ which is equivalent to $I^2\times R$ or $\frac{V^2}/R$, where $I$, $V$,
 and $R$ refer to current, voltage, and resistance of the resistor,
 respectively. 
 
-![A MOSFET device. When the gate voltage (VGS) of the MOSFET is below the
+![A MOSFET device. ](https://yueguoguo.github.io/images/mosfet.png) 
+<font size="1">When the gate voltage (VGS) of the MOSFET is below the
 threshold, there's minimal or no conduction between the drain and source
 terminals, rendering the switch off. However, with a more positive gate voltage,
 electrons are drawn, creating an n-type conductive channel beneath the oxide
 layer, enabling electron flow between the terminals and turning the switch
-on.](https://yueguoguo.github.io/images/mosfet.png) 
+on.</font>
 
 Given the complexity of the equivalent resistance of a MOSFET, in general, the
 power dissipation of a MOSFET is mainly due to its drain-source equivalent