ECAT Physics MCQs

Lens power is measured in dioptres.
Converging lenses have positive power and diverging lenses negative power.

For a spherical mirror, R=2f.
R=2×12 = 24 cm.

Magnetic fields are produced by magnets and moving charges.
Their direction is indicated by field lines.

Linear magnification compares image and object heights.
Its sign indicates image orientation under a chosen convention.

An object at 2f forms an image at 2f.
The mirror equation gives v=20 cm.

Refractive index generally depends on wavelength.
A prism therefore bends colors by different amounts.

Use f=c/λ with λ=600×10^-9 m.
F=3×10^8/(6×10^-7)=5×10^14 Hz.

For an open pipe, fundamental wavelength is 2L=1.7 m.
F=340/1.7 = 200 Hz.

For a closed pipe, fundamental wavelength is 4L=3.4 m.
F=340/3.4 = 100 Hz.

Reflection changes the direction of light at a boundary.
The incident and reflected rays remain in the same medium.

Angles are measured from the normal to the surface.
The incident ray, reflected ray, and normal lie in one plane.

Refraction occurs because wave speed changes across a boundary.
The frequency remains constant while wavelength changes.