ACSEE (Form 6) Electronics — practice questions

1. In the non-inverting configuration the input signal goes to the non-inverting terminal. 2. The feedback network of $R_f$ and $R_1$ sets how much of the output returns to the inverting input. 3. The resulting closed-loop gain is $A=1+\dfrac{R_f}{R_1}$. 4. The leading 1 means the gain can never fall below unity, and the output stays in phase with the input. 5. Dropping that 1 gives the inverting amplifier's gain magnitude instead, which is a different circuit. _Source: NECTA ACSEE 2023 Physics 131/1, Question 9: Electronics (Semiconductors,Logic Gates & Op-Amps)_

1. Reverse bias connects the positive supply terminal to the n-side and the negative to the p-side. 2. That pulls the majority carriers away from the junction rather than across it. 3. The depletion layer therefore widens, raising the barrier the carriers must cross. 4. Majority carriers are blocked, so only a very small leakage current from minority carriers flows. 5. Resistance in reverse bias is very high, not near zero, which is precisely why the diode conducts in only one direction. _Source: NECTA ACSEE 2023 Physics 131/1, Question 9: Electronics (Semiconductors,Logic Gates & Op-Amps)_

1. In a semiconductor most charge carriers are bound in covalent bonds at low temperature. 2. Heating supplies energy that breaks some of those bonds. 3. Each broken bond releases an electron and leaves a hole, so both carrier types increase. 4. More carriers means higher conductivity, so resistance falls as temperature rises. 5. This is the opposite of a metal, where extra lattice vibration scatters the already-free electrons and conductivity falls. _Source: NECTA ACSEE 2023 Physics 131/1, Question 9: Electronics (Semiconductors,Logic Gates & Op-Amps)_