Practice free Semiconductor Electronics: Materials, Devices and Simple Circuits (Physics) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
What is the approximate threshold voltage or cut-in voltage for a silicon diode?
The NCERT states, 'This voltage is called the threshold voltage or cut-in voltage (~0.2V for germanium diode and ~0.7 V for silicon diode).'
In reverse bias, the current flowing through a p-n junction diode is typically in the order of:
The NCERT text mentions, 'For the diode in reverse bias, the current is very small (~μA) and almost remains constant with change in bias. It is called reverse saturation current.'
The dynamic resistance ($r_d$) of a diode is defined as:
As per the NCERT, 'For diodes, we define a quantity called dynamic resistance as the ratio of small change in voltage ΔV to a small change in current ΔI: $r_d = \Delta V / \Delta I$ (14.6)'
What happens to the barrier potential of a p-n junction diode under forward bias?
The context states, 'The effective barrier height under forward bias is ($V_0 – V$).' Also, 'The barrier is decreased while the barrier increases in reverse bias.'
What happens to the depletion layer width of a p-n junction diode under reverse bias?
According to the NCERT, 'As a result, the barrier height increases and the depletion region widens due to the change in the electric field' in reverse bias.
Which of the following describes the nature of current in a p-n junction diode under reverse bias?
The NCERT states, 'The electric field direction of the junction is such that if electrons on p-side or holes on n-side in their random motion come close to the junction, they will be swept to its majority zone. This drift of carriers gives rise to current. Thedrift current is of the order of a few μA.'
The p-n junction diode primarily allows the flow of current in:
The context clearly states, 'The above discussion shows that the p-n junction diode primarily allows the flow of current only in one direction (forward bias).'
What is the typical magnitude of the total diode forward current?
The NCERT states, 'The magnitude of this current is usually in mA.' (referring to forward current).
What is 'minority carrier injection' in a p-n junction diode?
The NCERT explains, 'Due to the applied voltage, electrons from n-side cross the depletion region and reach p-side (where they are minority carries). Similarly, holes from p-side cross the junction and reach the n-side (where they are minority carries). This process under forward bias is known as minority carrier injection.'
Why is the forward bias resistance of a diode low compared to its reverse bias resistance?
The NCERT text states, 'The forward bias resistance is low as compared to the reverse bias resistance.' This is because 'in forward bias... the barrier is decreased' and 'in reverse bias... the barrier increases'.
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.