ECAT Physics MCQs

Power is reciprocal focal length in metres.
P=1/0.25 = 4 dioptres.

An ohmic conductor has V=IR under constant temperature and conditions.
Its V-I graph is linear through the origin.

Power is P=1/f.
P=1/(-0.50) = -2 D.

Series resistors carry the same current.
The voltage drops add to the source voltage.

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.