Sensors and interfaciing

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1. What type of sensor is shown in the photo below? a) an LDR b) an LED c) a photocell d) a thermistor.

2. The output of the sensor shown consists of: a) an output current b) a series of pulses c) a change in resistance d) logic levels (0 or 1).

3. What type of sensor is shown in the photo below? a) an LVDT b) a thermistor c) a strain gauge d) a thermocouple.

4. The output of the sensor shown consists of: a) an output voltage b) a series of pulses c) a change in resistance d) logic levels (0 or 1).

5. An optical shaft encoder is an example of: a) a light level sensor with a digital output b) a light level sensor with an analogue output c) an angular position sensor with a digital output d) an angular position sensor with an analogue output.

6. The output of the sensor interface shown below: a) goes low with increasing light level b) goes high with increasing light level c) goes low with increasing temperature d) goes high with increasing temperature.

7. In order to illuminate the LED in the circuit shown below: a) a logic 0 input is required b) a logic 1 input is required c) the input should be taken to 0V d) the input should be left unconnected.

8. The function of D1 in the circuit shown below is to: a) remove the back e.m.f. b) speed up the switching action c) an LED to indicate the state of the circuit d) a rectifier to enable correct operation with an a.c. supply.