ECAT Physics — Dawn of Modern Physics
Dawn of Modern Physics is part of the Physics section of the UET ECAT (30 of the 100 MCQs). It breaks into 5 subtopics, and we hold 21 ECAT-pattern practice MCQs on it, each with a written explanation. Tap a subtopic below to practise just that.
Subtopics (5)
How Dawn of Modern Physics is tested
Across the 7 ECAT past papers on ParhaiKrlo, Dawn of Modern Physics accounts for 7 questions. It appears in 4 of them, about 1.8 questions a paper. The heaviest was ECAT Past Paper 04, with 3 questions, and the most recent is ECAT Past Paper 07, with 2.
| Paper | Questions |
|---|---|
| ECAT Past Paper 07 | 2 |
| ECAT Past Paper 04 | 3 |
| ECAT Past Paper 03 | 1 |
| ECAT Past Paper 01 | 1 |
Dawn of Modern Physics MCQs from the ECAT past papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · ECAT Past Paper 07 · Dawn of Modern Physics
When a metal surface is exposed to light it may emit electrons. The maximum energy of these electrons depends on the:
- A.Intensity of light
- B.Area of metal surface
- C.Wavelength of light
- D.All of the above
Show answer
Answer: C. Wavelength of light — K.E.max = hc/λ − φ.
- Q2 · ECAT Past Paper 04 · Dawn of Modern Physics
When a metal surface is exposed to light it may emit electrons. The maximum energy of these electrons depends on the:
- A.Intensity of light
- B.Wavelength of light
- C.Area of the metal surface
- D.All of the above
Show answer
Answer: B. Wavelength of light — K.E.max = hc/λ − φ depends on the wavelength (frequency), not on intensity or area.
- Q3 · ECAT Past Paper 03 · Dawn of Modern Physics
When a metal surface is exposed to light it may emit electrons. The maximum energy of these electrons depends on the:
- A.Intensity of light
- B.Wavelength of light
- C.Area of metal surface
- D.All of the above
Show answer
Answer: B. Wavelength of light — K.E.max = hf − φ = hc/λ − φ, so it depends on the frequency (wavelength) of the light, not on intensity.