Figure shows the output characteristics of two different Bipolar Junction Transistors (BJT), BJT 1 with magnitude of Early voltage \(|V_{A1}|\), and BJT 2 with magnitude of Early voltage \(|V_{A2}|\).
Which of the following options is/are correct regarding the Early voltages?
Show Hint
Extend each curve's straight part back to the \(V_{CE}\) axis; a flatter curve corresponds to a larger, but still finite, Early voltage.
Step 1: Recall the geometric picture of the Early effect.
Draw a line through the sloped part of a BJT's $I_C$-$V_{CE}$ curve at fixed $I_B$ and extend it backward past the origin; it hits the $V_{CE}$ axis at $-V_A$. A curve that climbs fast has a small $V_A$. A curve that is almost level has a large $V_A$.
Step 2: Compare the steepness of the two curves.
In the figure, BJT 1's solid curve climbs clearly as $V_{CE}$ grows. BJT 2's dashed curve barely climbs at all over the same span. So BJT 1 is the steep one and BJT 2 is the flat one.
Step 3: Translate steepness into Early voltage size.
Steep means small $V_A$, so $|V_{A1}|$ is the smaller of the two. Flat means large $V_A$, so $|V_{A2}|$ is the bigger one. This gives $|V_{A1}| < |V_{A2}|$, matching option C and ruling out option A.
Step 4: Rule out an infinite Early voltage for BJT 1.
A truly infinite $V_{A1}$ would need the curve to be dead flat, with zero slope. BJT 1's curve is visibly slanted, so $V_{A1}$ is some finite, moderate number, not infinite. This kills option B.
Step 5: Confirm BJT 2's Early voltage is still finite.
BJT 2 looks nearly flat, but a real device always has some Early effect, so its output resistance, however large, is never infinite. That keeps $|V_{A2}|$ a large but finite number, so option D holds.
Step 6: Conclude.
\[ \boxed{|V_{A1}| < |V_{A2}| \text{ and } |V_{A2}| \text{ is finite}} \]
