MCQ Collection
ECAT Physics MCQs
Practice ECAT Physics questions with answers and explanations.
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Correct Answer: B. Reciprocal of focal length in metres
Explanation:
Lens power is measured in dioptres.
Converging lenses have positive power and diverging lenses negative power.
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Correct Answer: B. 24 cm
Explanation:
For a spherical mirror, R=2f.
R=2×12 = 24 cm.
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Correct Answer: B. A region where magnetic forces act on magnets or moving charges
Explanation:
Magnetic fields are produced by magnets and moving charges.
Their direction is indicated by field lines.
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Correct Answer: C. Ratio of image size to object size
Explanation:
Linear magnification compares image and object heights.
Its sign indicates image orientation under a chosen convention.
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Correct Answer: C. 20 cm
Explanation:
An object at 2f forms an image at 2f.
The mirror equation gives v=20 cm.
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Correct Answer: D. Separation of light into components of different wavelengths
Explanation:
Refractive index generally depends on wavelength.
A prism therefore bends colors by different amounts.
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Correct Answer: D. 5 × 10^14 Hz
Explanation:
Use f=c/λ with λ=600×10^-9 m.
F=3×10^8/(6×10^-7)=5×10^14 Hz.
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Correct Answer: A. 200 Hz
Explanation:
For an open pipe, fundamental wavelength is 2L=1.7 m.
F=340/1.7 = 200 Hz.
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Correct Answer: B. 100 Hz
Explanation:
For a closed pipe, fundamental wavelength is 4L=3.4 m.
F=340/3.4 = 100 Hz.
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Correct Answer: C. Return of light into the same medium after striking a surface
Explanation:
Reflection changes the direction of light at a boundary.
The incident and reflected rays remain in the same medium.
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Correct Answer: D. Angle of incidence equals angle of reflection
Explanation:
Angles are measured from the normal to the surface.
The incident ray, reflected ray, and normal lie in one plane.
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Correct Answer: A. Change in direction of light when it changes speed between media
Explanation:
Refraction occurs because wave speed changes across a boundary.
The frequency remains constant while wavelength changes.