Reverse Bias Blocks - Electricity and Electronic Circuits Step by Step

This reverse-bias-blocks lesson uses the same source and limiter but flips the diode orientation, so the ideal branch current is zero. The blocked rows are exact only for the ideal diode model and the stated source-voltage table, not for breakdown or leakage behavior. Real devices include reverse leakage, breakdown limits, capacitance, temperature dependence, tolerances, finite precision, and measurement uncertainty.

Reversing the diode orientation blocks the branch in this ideal model. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Forward bias conducts in this model

With the diode direction aligned to the source, the branch carries 2 amperes.

I_{\text{forward}} = 2\ \text{A}

Reverse bias removes the conducting path

Flip only the diode orientation. The same source and limiter no longer form a conducting branch through the diode.

\text{reverse bias} \Rightarrow \text{blocked branch}

The reverse current is zero

The reverse-biased ideal diode gives a branch current of 0 amperes. No KVL loop is claimed through the reversed diode.

I_{\text{reverse}} = 0\ \text{A}

Blocked stays blocked across source sizes

The reverse-biased branch remains nonconducting for these exact training source values. The diagram shows the middle row.

\begin{array}{c|c|c|c|c}V_s&V_f&R&V_R&I\\6\ \text{V}&2\ \text{V}&5\ \text{ohm}&0\ \text{V}&0\ \text{A}\\12\ \text{V}&2\ \text{V}&5\ \text{ohm}&0\ \text{V}&0\ \text{A}\\18\ \text{V}&2\ \text{V}&5\ \text{ohm}&0\ \text{V}&0\ \text{A}\\\end{array}