A-LevelPhysicsElectricity9702/42 · Oct/Nov 2020 · Q86 Marks
An ideal operational amplifier (op-amp) is said to have infinite bandwidth and infinite slew rate. The resistance of resistor R is to be fixed so that, for an input potential difference V_IN of 0.40 V, the amplifier is on the point of saturation. Determine:
- (a)(i)infinite bandwidth[1]
- (a)(ii)infinite slew rate.[1]
- (b)(i)the gain of the amplifier circuit[2]
- (b)(ii)the resistance of resistor R.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.
- [B1] gain is the same for all frequencies
- [B1] no (time) delay in change in output when input is changed
- [C1] (at saturation,) VOUT = 5.0 V
- [A1] gain = 5.0/0.40, = 12.5 or 13
- [C1] 12.5 = 1 + (R/800)
- [A1] R = 9200 Ω
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