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Physics
A. Atoms move faster
B. Coulomb barrier must be overcome
C. Gravity increases
D. Neutrons are released
Answer: Nuclei must have enough kinetic energy to overcome the Coulomb repulsion between positively charged nuclei.
Physics
A. Parallel to the magnetic field
B. Perpendicular to the magnetic field
C. At 45° to the field
D. At 60° to the field
Answer: When the plane is parallel to the field, the area vector is perpendicular, giving maximum torque τ = M × B.
Physics
A. 92
B. 143
C. 235
D. 327
Answer: Number of neutrons = Mass number - Atomic number = 235 - 92 = 143
Physics
A. LI²
B. ½LI²
C. LI
D. ½LI
Answer: Energy stored in inductor = ½LI², analogous to energy stored in capacitor = ½CV².
Physics
A. Frequency of AC voltage
B. Magnetic field and radius of dees
C. Only the mass of particle
D. Only the charge of particle
Answer: KE_max = q²B²R²/(2m), depending on magnetic field B and radius R of the dees.
Physics
A. 1.24 eV
B. 2.48 eV
C. 3.72 eV
D. 0.62 eV
Answer: φ = hc/λ₀ = 12400/5000 = 2.48 eV
Physics
A. Amplitude only
B. Frequency only
C. Square of amplitude
D. Wavelength
Answer: Energy density u = ε₀E² = ε₀E₀² sin²(ωt-kx), proportional to the square of the amplitude.
Physics
A. Steady current
B. Change in current
C. Voltage
D. Resistance
Answer: Self-inductance produces a back EMF that opposes any change in current (Lenz\'s law applied to self-induction).
Physics
A. Are accelerated
B. Hit a metal target
C. Are deflected by magnetic field
D. Combine with protons
Answer: X-rays are produced when high-speed electrons are suddenly decelerated upon striking a metal target.
Physics
A. Parallel
B. Perpendicular to each other and to propagation
C. At 45° to each other
D. In the same direction
Answer: In EM waves, E and B fields are perpendicular to each other and both are perpendicular to the direction of wave propagation.
Physics
A. 0
B. 1
C. 0.5
D. Infinity
Answer: At resonance, Z = R (minimum), so power factor cos φ = R/Z = 1. Circuit behaves as purely resistive.
Physics
A.
B. 45°
C. 90°
D. 60°
Answer: tan φ = XC/R = 10/10 = 1 → φ = tan⁻¹(1) = 45°. Current leads voltage.
Physics
A. 13.6 eV
B. 3.4 eV
C. 10.2 eV
D. 6.8 eV
Answer: ΔE = 13.6(1 - 1/4) = 13.6 × 3/4 = 10.2 eV
Physics
A. Energy density
B. Energy flux density (power per unit area)
C. Magnetic flux
D. Electric flux
Answer: Poynting vector S = E × B/μ₀ represents the directional energy flux (power per unit area) of the EM wave.
Physics
A. 3 × 10^8 m/s
B. 3 × 10^6 m/s
C. 3 × 10^10 m/s
D. 3 × 10^5 m/s
Answer: All electromagnetic waves travel at c = 3 × 10^8 m/s in vacuum.
Physics
A. 7 Ω
B. 1 Ω
C. 5 Ω
D. 12 Ω
Answer: Z = √(R² + XL²) = √(9 + 16) = √25 = 5 Ω
Physics
A. Faraday
B. Maxwell
C. Ampere
D. Gauss
Answer: Maxwell introduced the concept of displacement current to make Ampere\'s law consistent for time-varying fields.
Physics
A. 1.097 × 10^7 m⁻¹
B. 6.674 × 10⁻¹¹ N·m²/kg²
C. 8.987 × 10^9 N·m²/C²
D. 9.109 × 10⁻³¹ kg
Answer: R = 1.097 × 10^7 m⁻¹ is the Rydberg constant used in the hydrogen spectral series formula.
Physics
A. Total energy released
B. Mass of products
C. Kinetic energy of products
D. Binding energy of products
Answer: Q-value = (mass of reactants - mass of products)c² = total energy released in the nuclear reaction.
Physics
A. Lyman series line
B. Balmer series line
C. Paschen series line
D. Brackett series line
Answer: Transitions to n=2 produce the Balmer series (visible light region).