1. St Columba’s High School Electricity and Electronics Op-amps

2. An op amp is : 1. A frequency amplifier 2. A current amplifier 3. A voltage amplifier 4. A power amplifier

3. In the ideal op amp shown what is a) the potential at and b)the current flowing into the inverting pin ? 1. 0.5 V and 0 mA 2. 0 V and 0.05 mA 3. 0.5 V and 0.05 mA 4. 0 V and 0 mA

4. Calculate V out 1. 5.0 V 2. - 0.05 V 3. -5.0 V 4. 0.05 V

5. What is the value of V out if V in = 2.0 V ? 1. -20 V 2. + 0.2 V 3. -13.5 V 4. +13.5 V

6. The input voltage has a frequency of 280 Hz and a peak value of 0.5 V. The frequency of the output voltage is : 1. 14 Hz 2. 28 Hz 3. 280 Hz 4. 560 Hz

7. If the variable resistor is altered over the range 0 to 200 kΩ what is the range of the gain ? 1. 0 to 1 2. 0 to 10 3. 1 to 10 4. 1 to 11

8. What is the gain expression for the differential mode ? 1. ( V 1 – V 2 )x 10 2. ( V 2 - V 1 )x - 10 3. ( V 2 – V 1 )x 10 4. ( V 1 – V 2 )x -10

9. The 5 V bulb does not light properly because : 1. V out is negative 2. I out is zero amps 3. V out is positive 4. I out is in the micro amp range

10. Calculate R 1 if V out = 2.5 V 1. 50 kΩ 2. 20 kΩ 3. 5 kΩ 4. 2 kΩ

11. Calculate the unknown resistance if the amp is operating in the differential mode : 1. 0.4 kΩ 2. 10 kΩ 3. 5 kΩ 4. 50 kΩ

12. Calculate the value of V 2 – V 1 if V out = 10 V 1. 2 V 2. - 2V 3. 1.25 V 4. - 1.25 V

13. Calculate V 1. V out = 500 mV and V 2 =90 mV 90 1. 130 mV 2. -40 mV 3. -130 mV 4. 40 mV 500 mV 90 mV V1V1