Which phenomenon explains the blue color of the sky?
ATotal internal reflection
BRayleigh scattering
CMie scattering
DInterference
Correct Answer:
B. Rayleigh scattering
EXPLANATION
Rayleigh scattering causes shorter blue wavelengths to scatter more effectively than longer red wavelengths when sunlight passes through the atmosphere, making the sky appear blue.
AAn alpha particle is a helium nucleus with 2 protons and 2 neutrons
BAlpha decay increases the atomic number
CAlpha particles have high penetration power
DAlpha decay produces beta particles
Correct Answer:
A. An alpha particle is a helium nucleus with 2 protons and 2 neutrons
EXPLANATION
An alpha particle is a helium-4 nucleus (₂He⁴) with 2 protons and 2 neutrons. Alpha decay decreases atomic number by 2 and mass number by 4. Alpha particles have low penetration power.
A transformer has 100 turns in the primary coil and 500 turns in the secondary coil. If the primary voltage is 220V, what is the secondary voltage assuming 100% efficiency?
A44 V
B220 V
C1100 V
D2200 V
Correct Answer:
C. 1100 V
EXPLANATION
Using transformer equation: Vₛ/Vₚ = Nₛ/Nₚ. Vₛ = 220 × (500/100) = 220 × 5 = 1100 V.
Correct Answer:
B. Tungsten filament in a light bulb
EXPLANATION
A tungsten filament's resistance changes significantly with temperature during operation, making it non-ohmic. Metals at constant temperature follow Ohm's law.