A = ρ * (L / R) = 3 x 10^-6 * (4 / 12) = 1 mm².

Resistance R is proportional to length; if length doubles, resistance also doubles to 24 Ω.

R = R0(1 + α(T - T0)) = 5(1 + 0.004(100 - 20)) = 6.4 Ω.

Resistance is directly proportional to resistivity; hence, wire B with higher resistivity will have higher resistance.

Resistance R = ρ(L/A). For wire A, R_A = ρ(2L/(A/2)) = 4ρ(L/A) = 4R_B.

Resistivity ρ = R * (A / L) = 3 * (2 x 10^-6 / 10) = 1.5 x 10^-6 Ω·m.

The extension of the wire can be calculated using the formula: extension = (F * L) / (A * Y).

The elongation ΔL of a wire is given by ΔL = FL / (AE), where E is Young's modulus.

The elongation ΔL of a wire is given by ΔL = (F * L) / (A * Y), where Y is Young's modulus.

Ampere's Law states that the line integral of the magnetic field B around a closed path is equal to μ₀ times the total current I enclosed by the path.

Ampere's Law states ∮B·dl = μ₀I_enc, where I_enc is the enclosed current.

Ampere's Law states that the line integral of B around a closed loop is μ₀ times the total current through the loop.

Inside a long straight conductor, the magnetic field is zero because the contributions from all parts of the conductor cancel out.

Charles's Law states that the volume of a gas is directly proportional to its absolute temperature at constant pressure, expressed as V ∝ T.

Charles's Law states that the volume of a gas is directly proportional to its absolute temperature at constant pressure, meaning that as temperature increases, volume also increases.

Faraday's law states that the induced EMF is directly proportional to the rate of change of magnetic flux through the circuit.

Faraday's law states that the induced EMF is directly proportional to the rate of change of magnetic flux through the circuit.

According to Kirchhoff's Current Law, the total current entering a junction equals the total current leaving it. Total entering = 2A + 3A + 4A = 9A.

According to Kirchhoff's Current Law, the sum of currents entering a junction equals the sum of currents leaving. Therefore, I_out = 2A + 3A + 4A = 9A.

According to Kirchhoff's Current Law, total current entering = total current leaving. 2A + 3A + 1A = 6A.

According to Kirchhoff's Current Law, the total current entering a junction equals the total current leaving it. Therefore, total current leaving = 2A + 3A + 5A = 10A.

Kirchhoff's Voltage Law states that the sum of the electromotive forces and potential differences in any closed loop is zero.

Kirchhoff's Voltage Law states that the sum of the electrical potential differences (voltage) around any closed circuit is zero.

Newton's third law states that for every action, there is an equal and opposite reaction.

The magnetic field dB is proportional to Idl and sin(θ), where θ is the angle between the current element and the line connecting the current element to the point of interest.

The pressure exerted by a gas is due to the collisions of gas molecules with the walls of the container, which transfers momentum to the walls.

The pressure of a gas is caused by the collisions of gas molecules with the walls of the container, which exert force on the walls.

The pressure exerted by a gas is due to the collisions of gas molecules with the walls of the container.

Using the formula: h = 0.5 * g * t². 80 = 0.5 * 10 * t². Solving gives t² = 16, so t = 4 s.

Using the formula: h = 0.5 * g * t², where h = 80 m and g = 9.8 m/s². Solving for t gives t = sqrt(2h/g) = sqrt(2*80/9.8) ≈ 4.04 s, approximately 4 s.