Natwerk Designs

Help me with these Microwave questions :(?

1. At what frequency does a microwave oven operate? A. 450 kHz C. 915 MHz B. 2450 kHz D. 2450 MHz 2. To prevent a high-voltage capacitor from retaining a charge, most modern microwave ovens use a discharge device called a A. bleeder resistor. C. terminating TRIAC. B. discharge diode. D. end-of-cycle transistor. 3. The forward voltage, peak reverse voltage, and the forward current are ratings used to describe which of the following components? A. Thermal protector C. High-voltage capacitor B. Magnetron tube D. High-voltage diode 4. The combination of a capacitor and diode in the magnetron’s high-voltage circuit make a circuit known as a A. frequency stabilizer. C. buffer. B. frequency doubler. D. voltage doubler. 5. The internal tuned cavities of a magnetron tube are responsible for A. causing the electron to orbit the anode. B. doubling the microwave output from the tube. C. causing the electrons to resonate, creating the microwave frequency. D. cooling the tube by creating extra internal surface area. 6. What material is used for the dome that encapsulates the magnetron tube’s antenna? A. Plastic C. Copper B. Steel D. Glass 7. On a manually set timer-controlled oven with a variable-power selector, what types of devices are used to control the AC power to the magnetron’s power transformer? A. A self-triggering TRIAC C. A pulsing-timer contact B. A power-selector relay D. A motor and a switch 8. What DC voltage will normally be on the magnetron’s plate, or anode? A. Ground C. 2000 volts B. 3.5 volts D. 4000 volts 9. If the primary and secondary interlock switches fail closed, what device prevents the oven from operating with the door open? A. Control relay C. Monitor switch B. Power-level TRIAC D. Light switch 10. Which one of the following is a disadvantage of a nonconvection microwave oven? A. It will require more energy to cook food. B. It will not brown foods. C. It takes a long time to heat food. D. It will not defrost frozen foods. 11. What is the maximum output wattage of a conventional microwave oven? A. 200 watts C. 1000 watts B. 500 watts D. 2000 watts 12. A magnetron tube does NOT contain a cathode element as does a normal vacuum-tube diode. What component of the tube is heated to produce electron flow instead of the cathode? A. A series of coated rods C. A coated cavity B. A coated sleeve D. The permanent magnets 13. One lead of the high-voltage diode always connects to the high-voltage capacitor. Where does the other lead connect? A. To the control relay C. To chassis ground B. To the power-level relay D. To the magnetron’s filament 14. Which one of the following oven components is used to spread the microwave energy around the inside of the oven? A. The fan or blower C. The waveguide B. The stirrer fan D. The spreader assembly 15. What AC voltage will normally be found on the filament winding of a magnetron’s tube? A. 3.5 C. 2000 B. 1250 D. 4000 16. How does a touch keypad tell a microprocessor-controlled system which key is pressed? A. Each key has an individual wire set that connects to the microprocessor. B. Each key outputs a specific frequency when it is pressed. C. Each key outputs a specific voltage level which is particular to only that key. D. Each key connects to a matrix of row and column lines which are decoded by the microprocessor. 17. In a TRIAC power-level system, why is on- and off-type triggering used instead of speed-control-type triggering? A. On and off triggering generates less component heat. B. On and off triggering is less expensive to design and build. C. On and off triggering allows for proper voltages to be supplied to the magnetron. D. On and off triggering creates much less electrical noise. 18. A microwave oven may contain up to three thermal protectors. One is mounted on the magnetron’s case assembly and a second is mounted on the rear of the oven cavity. Where is the third thermal protector mounted? A. On the ECM module C. Near the fan or blower assembly B. In the waveguide D. On the power transformer 19. Some inexpensive microwave ovens use a vari-power motor and a vari-power switch to control oven power. What is another method of creating an inexpensive power-level control system? A. Using a second cam switch on the timer B. Mounting a gearbox-driven switch actuator off of the blower fan C. Mounting a switch in the gearbox of the turntable D. Placing a timer relay in the control circuit 20. What is the purpose of a driver transistor on a microprocessor control board? A. It lights the elements in the display. B. It triggers the TRIAC module. C. It regulates the DC voltage on the board. D. It changes the low-power output of the IC to a higher current output to drive a relay.

Public Comments

1. The questions appear to be sneaky: 1C but this is higher than the frequency used in old microwaves 2A, but any of the others are possible 3D but 3B the magnetron could be rated with that terminology 10B 15A
2. 1D,2A,3D,4B,5C,6D,7B,8C,9A,10B,11D,12D, 13?,14D,15A.16D,17A,18D,19D,20B
3. 1.B 2.A 3.D 4.B 5.C 6.C 7.B 8.D 9.C 10.B 11.C 12.B 13.C 14.D 15.A 16.A 17.C 18.D 19.C 20.D