Govt. Exams
Entrance Exams
Resistance of element R = V²/P = 220²/1000 = 48.4Ω (constant). At 110V: P' = V'²/R = 110²/48.4 ≈ 250W. Power varies with square of voltage.
When stretched, length becomes 1.5L. Volume remains constant (LA = A'L'), so A' = A/1.5. New resistance R' = ρ(1.5L)/(A/1.5) = 2.25ρL/A = 2.25R
P = V²/R. New P = (2V)²/(R/2) = 4V²×2/R = 8(V²/R) = 8P₀
Tungsten filament's resistance increases significantly with temperature due to heating, causing non-linear I-V characteristic (non-ohmic).
In DC circuits, current is continuous (same) through all series elements including capacitors in steady state. However, in AC circuits, current flows through capacitors.
V = E - Ir. 9 = 10 - I×r. Current I = V/R = 9/90 = 0.1A. So 9 = 10 - 0.1r, giving r = 10Ω
In meter bridge: R₁/R₂ = l₁/(100-l₁). So 8/R₂ = 40/60, giving R₂ = 12Ω
Heat dissipated H = I²Rt. Since same current flows through both and nichrome has higher resistivity than copper (higher R), nichrome dissipates more heat.
E₁/E₂ = l₁/l₂. So E₂ = E₁(l₂/l₁) = 1.5(80/60) = 2V
Terminal voltage V = E - Ir, where I is the current through the circuit. The voltage drop occurs only across internal resistance.
