MDCAT Physics MCQs

For two parallel resistors, R=R1R2/(R1+R2).
R=18/9 = 2 Ω.

For a uniform field, flux is BA cosθ.
Its SI unit is the weber.

AC reverses direction with time.
Mains electricity is commonly sinusoidal alternating current.

Transformers use changing magnetic flux in coupled coils.
They ideally conserve power while changing voltage and current.

Use F=kq1q2/r² with charges in coulombs.
F=9×10^9×2×10^-6×3×10^-6 = 0.054 N.

Coulomb force varies inversely with distance squared.
Tripling distance multiplies force by 1/3² = 1/9.

Electric field is force per unit charge.
E=20/4 = 5 N/C.

Electrical work is W=QV.
W=2×12 = 24 J.

Charge is Q=It.
Q=3×20 = 60 C.

Current is charge divided by time.
I=120/30 = 4 A.

Magnetic force is qvB sinθ in magnitude.
It changes direction of motion but does no work on the charge.

Faraday's law links induced emf to the rate of magnetic-flux change.
Relative motion or changing current can produce induction.