Advanced Qualification · A-003 Measurements · A-003-005-001
If a 100 Hz signal is fed to the horizontal input of an oscilloscope and a 150 Hz signal is fed to the vertical input, what type of pattern should be displayed on the screen?
- A An oval pattern 100 mm wide and 150 mm high
- B A looping pattern with 100 horizontal loops and 150 vertical loops
- C A looping pattern with 3 horizontal loops, and 2 vertical loops
- D A rectangular pattern 100 mm wide and 150 mm high
Correct answer: C — A looping pattern with 3 horizontal loops, and 2 vertical loops. From the official ISED question bank, verified word for word.
Why
When you feed a 100 Hz signal to the horizontal input and a 150 Hz signal to the vertical input of an oscilloscope, the screen draws a looping shape called a Lissajous figure. The full explanation — and one for every question — is in Pro.
Practise this section
Measurements: meters, oscilloscopes, counters, signal generators, and what a reading actually tells you.