H2 Physics Flashcards

What is Coulomb's Law?

Answer: F = kQ₁Q₂/r²

Coulomb's Law: F = kQ₁Q₂/r² (or F = Q₁Q₂/4πε₀r²), giving the electrostatic force between two point charges, where k = 9×10⁹ N m² C⁻².

A particle of charge q moves with velocity v perpendicular to a magnetic field B. What force acts on it?

Answer: F = qvB

The magnetic force on a moving charge: F = qvB sin θ. When velocity is perpendicular to B (θ = 90°), sin θ = 1, so F = qvB.

What is meant by 'half-life' in radioactive decay?

Answer: The time for the activity (and number of undecayed nuclei) to halve

Half-life (t½) is the time taken for the number of undecayed nuclei (or the activity) of a radioactive sample to decrease to half its original value.

A simple pendulum has period T = 2π√(L/g). If L is quadrupled, how does T change?

Answer: T doubles

T ∝ √L. If L is quadrupled (×4), T changes by √4 = 2. So T doubles.

What is the phenomenon of 'interference' in waves?

Answer: The superposition of two coherent waves producing regions of constructive and destructive interference

Wave interference occurs when two coherent waves superpose: where crests meet (in phase), constructive interference creates large amplitude; where crest meets trough (antiphase), destructive interference creates zero amplitude.

What is the relationship between electric field strength E and potential V?

Answer: E = -dV/dr

Electric field strength is the negative rate of change of electric potential: E = -dV/dr (or E = -ΔV/Δr for uniform fields). The field points in the direction of decreasing potential.