1. Twenty Questions Electronics

2. Twenty Questions 12345 678910 1112131415 1617181920

3. 1. At the start of the experiment, the ammeter reading is 0.02A, at the end it is 0.15A Resistance has decreased as the current has increased. I=V/R, where V is constant. T A Explain whether the resistance of the component show has increased or decreased.

4. 2. Of what 3 main parts does an electronic system consist? Input Process Output

5. 3. Name the component & explain how it works. Thermistor Temperature Up Resistance Down

6. 4. Select suitable input and output devices for a baby monitor. Input – Microphone Output - Loudspeaker

7. 5. Give 3 input devices Dimmer switch. Volume control on radio. Heat dial on cooker. Light sensor, solar cell, LDR, Thermistor, Microphone, Thermocouple, switch

8. 6. What does an electrical relay do? Switches on and off a separate electrical circuit which might have high current or voltage.

9. 7. Name & state the function of the component. Transistor Electronic switch which automatically switches ON at 0.7V.

10. 8. Why would you use an LED instead of a filament to indicate that an electrical appliance was switched on? Less heat produced. Lower energy usage. Smaller.

11. 9. Calculate the current if the light level is 25lux. I = V/R I = 9/60 I = 0.15A A 9V Light levelResistance 15120 2080 2560

12. 10. How can the frequency of a clock pulse generator be increased? Decrease the value of the capacitor Decrease the value of the resistor.

13. 11. Name the component & explain how it works. LDR (light dependent resistor) Light Up Resistance Down

14. 12. Give the energy change for the following. Solar cell Microphone Thermistor LDR Light Electrical Sound Electrical Heat Electrical Light Electrical

15. 13. The LED has a voltage 2V. What is the value of R? V R = 12-2 =10V R = V R / I = 10/2.5 = 4Ω 12V 2.5A R

16. 14. Why is a resistor always put in series with an LED? To limit the current so the LED does not melt.

17. 15. Name 3 output devices Relay, loudspeaker, Light bulb, LED, Heater, Buzzer

18. 16. What happens to the value of V 2 as R 1 increases? V 2 decreases 0V 10V V2V2 R1R1 R2R2

19. 17. If R 1 =10kΩ and R 2 =2.5kΩ calculate V 2. 0V 10V V2V2

20. 18. Which component is used for a time delay? Capacitor. Voltage

21. 19. Draw a circuit showing which way an LED should be connected to a battery + -

22. 20. Give the energy change for the following. LED Solenoid Relay Loudspeaker Electrical Light Electrical Kinetic Electrical Sound