ECAT Physics — Waves
Waves is part of the Physics section of the UET ECAT (30 of the 100 MCQs). It breaks into 5 subtopics, and we hold 43 ECAT-pattern practice MCQs on it, each with a written explanation. Tap a subtopic below to practise just that.
Subtopics (5)
How Waves is tested
Across the 7 ECAT past papers on ParhaiKrlo, Waves accounts for 20 questions. It appears in all 7, about 2.9 questions a paper. The heaviest was ECAT Past Paper 06, with 4 questions, and the most recent is ECAT Past Paper 07, with 3.
| Paper | Questions |
|---|---|
| ECAT Past Paper 07 | 3 |
| ECAT Past Paper 06 | 4 |
| ECAT Past Paper 05 | 4 |
| ECAT Past Paper 04 | 2 |
| ECAT Past Paper 03 | 3 |
| ECAT Past Paper 02 | 3 |
| ECAT Past Paper 01 | 1 |
Waves MCQs from the ECAT past papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · ECAT Past Paper 07 · Waves
The density of oxygen is about 16 times that of hydrogen. If the speed of sound in hydrogen is x, then in oxygen (same temperature and pressure) it is:
- A.Greater than x
- B.Less than x
- C.The same as x
- D.None of these
Show answer
Answer: B. Less than x — v ∝ 1/√ρ at the same pressure: v(O₂) = x/4.
- Q2 · ECAT Past Paper 06 · Waves
An astronaut in space comes to know of an explosion on a nearby planet. The astronaut came to know about the explosion because:
- A.The astronaut saw, heard and felt the explosion
- B.The astronaut only saw the explosion
- C.The astronaut only heard the explosion
- D.The astronaut both saw and heard the explosion
Show answer
Answer: B. The astronaut only saw the explosion — Light travels through the vacuum of space, but sound needs a medium, so the explosion can only be seen.
- Q3 · ECAT Past Paper 05 · Waves
The density of oxygen is about 16 times that of hydrogen. If the speed of sound in hydrogen is x, then the speed of sound in oxygen is:
- A.Greater than x
- B.The same
- C.Less than x
- D.Depending upon the pressure of the gases
Show answer
Answer: C. Less than x — v ∝ 1/√ρ at the same pressure: v(O₂) = x/√16 = x/4, which is less than x.