An ideal operational amplifier (op-amp) has infinite bandwidth and zero output impedance.

1. (a)(i)State what is meant by: infinite bandwidth[1]
2. (a)(ii)zero output impedance.[1]
3. (b)(i)The circuit for a non-inverting amplifier incorporating an ideal op-amp is shown in [Figure 7.1]. The light-emitting diode (LED) emits light when the potential difference across it is at least 2.0 V. The current in the LED must not be greater than 20 mA. Calculate the gain of the amplifier circuit. gain = ...........................................................[2]
4. (b)(ii)Determine the value of V_IN for which the value of V_OUT is +2.0V. V_IN = ........................................................... V[1]
5. (b)(iii)State the maximum value of the output potential V_OUT. maximum potential = ........................................................... V[1]
6. (b)(iv)When the op-amp is saturated, the potential difference across the LED is 2.2V. Calculate the minimum resistance of resistor R so that the current in the LED is limited to 20 mA. resistance = ........................................................... Ω[2]

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