FBISE Class 9th (SSC-l)
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FBISE Class 9th (SSC-l)
Answer: Energy in nuclear reactions comes from the conversion of mass defect (lost mass) to energy via E = mc².
Answer: Iron-56 has the highest binding energy per nucleon (~8.8 MeV), making it the most stable nucleus.
Answer: Nuclear fusion involves the combination of light nuclei to form a heavier nucleus with release of energy.
Answer: White light produces a central white fringe with colored fringes on either side due to wavelength-dependent interference.
Answer: For constructive interference in thin films, 2μt = nλ (with phase change consideration at one surface).
Answer: The maximum order n is limited by d sin θ = nλ, where sin θ ≤ 1, so n ≤ d/λ.
Answer: By Malus\'s law: I = I₀ cos²θ = I₀ cos²45° = I₀ × (1/√2)² = I₀/2
Answer: Kirchhoff\'s junction rule states ΣI = 0 at any junction, based on conservation of charge.
Answer: Kirchhoff\'s loop rule states ΣV = 0 around any closed loop, based on conservation of energy.
Answer: Wheatstone bridge is balanced when P/Q = R/S, making the galvanometer reading zero.
Answer: E = hf = hc/λ, where h is Planck\'s constant and f is the frequency of the photon.
Answer: λ = h/√(2meV) = 1.227/√V nm. For V = 100, λ = 1.227/10 = 0.1227 nm ≈ 0.123 nm
Answer: Length contraction: L = L₀√(1-v²/c²). Moving objects appear shorter in the direction of motion.
Answer: Relativistic mass: m = m₀/√(1-v²/c²). Mass increases with velocity.
Answer: Time dilation: Δt = Δt₀/√(1-v²/c²). Moving clocks run slower than stationary ones.
Answer: Einstein\'s mass-energy equivalence: E = mc², where c is the speed of light.
Answer: KE_max = hf - φ, so maximum kinetic energy depends on the frequency of incident light, not its intensity.
Answer: The energy needed to remove an electron from ground state (n=1) is 13.6 eV.
Answer: Bohr\'s quantization condition: L = nh/2π = nℏ, where ℏ = h/2π.
Answer: Alpha particles are helium nuclei (⁴He²⁺) with mass number 4 and charge +2e.