A negative voltage is commonly applied to...

🔍 Key Concepts

• Magnetron structure: relationship between cathode, anode block, and cavities • High-voltage safety: why one side of a high-voltage system is often kept near ground potential • Direction of electron flow in vacuum tubes (from cathode to anode) and what sign of voltage is needed to make that happen

💭 Think About

• Think about which part of the magnetron (cathode or anode) is easier and safer to connect to the ship’s ground or chassis. • Ask yourself: if we choose to make one electrode very high voltage and the other close to zero (ground), which choice reduces shock hazard to personnel and simplifies shielding? • Consider how electrons move inside the magnetron. Does making the cathode negative or the anode positive change where the dangerous high voltage ends up relative to the radar chassis?

✅ Before You Answer

• Verify which electrode (cathode or anode) is typically operated at or near ground potential in many high-voltage tube circuits. • Confirm that changing the polarity of the supply doesn’t significantly change the magnetic field strength, but does change where the high voltage appears. • Eliminate any options that incorrectly describe electron motion (electrons do not move from positive to negative in a vacuum tube).

A negative voltage is commonly applied to the magnetron cathode rather than a positive voltage to the magnetron anode because:

The cathode must be made neutral to force electrons into the drift area.

A positive voltage would tend to nullify or weaken the magnetic field.

The anode can be operated at ground potential for safety reasons.

The cavities might not be shock-excited into oscillation by a positive voltage.

🔍 Key Concepts

💭 Think About

✅ Before You Answer