Diode V–I Characteristics Challenge
25 NEET-standard questions on the forward and reverse V–I characteristics of a p-n diode, threshold and breakdown voltage, dynamic resistance, and diodes in series circuits. Answer each one. If you get it wrong, Vidya Ma’am explains it with an animated movie you can control, a slider to play with, and a step-by-step solution. Then try again.
NCERT Physics XII Part II · Ch. 14 · pp. 336–337Keys: A–D or 1–4 to answer
🧠 Formula memory tricks (open before you start)
Threshold voltageSi ≈ 0.7 V · Ge ≈ 0.2 VBelow it the forward current is almost zero; above it the current rises steeply
Reverse sideIrev ≈ µA, flat until VbrSet by minority carriers, not by the voltage
Dynamic resistancerd = ΔV / ΔIThe reciprocal of the I–V slope (change ÷ change), not V / I at one point
Series circuitI = (E − Vth) / RIdeal diode: Vth = 0 forward, open switch in reverse
Resistancesrfb ≈ 10 Ω, rrb ≈ 10⁷ ΩNCERT Example 14.4: a one-way valve
Safe useKeep the current below the rated value, forward or reverseA series resistor limits it
right first tryfixed after explanationstill to fix
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