ECAT MCQs

Use 1/f=1/do+1/di.
1/di=1/10-1/30=1/15, so di=15 cm.

Parallel resistors share the same voltage.
The total resistance is less than the smallest branch resistance.

The object is at twice the focal length.
Using the lens equation gives di=40 cm.

Electrical power can be written P=VI.
It may also be expressed as I²R or V²/R.

Magnification magnitude is image height divided by object height.
30/10 = 3.

A capacitor consists of separated conductors.
Its capacitance measures charge stored per unit potential difference.

Image height equals magnification times object height.
Hi=-2×5=-10 cm, indicating inversion.

Capacitance is C=Q/V.
Its SI unit is the farad.

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.