Spring-mass period in orbiting satellite: MCQ with Answer and Explanation
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Question #1
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At the magnetic poles of the Earth, the angle of dip (inclination) is exactly:
Correct Answer: Option B
Explanation:
The angle of dip is the angle the Earth's total magnetic field vector makes with the horizontal surface. At the magnetic equator, the magnetic field lines are perfectly parallel to the ground (0 degrees). At the magnetic poles, the field lines plunge strictly vertically downward (or upward) into the ground, making a 90-degree angle with the horizontal.
The angle of dip is the angle the Earth's total magnetic field vector makes with the horizontal surface. At the magnetic equator, the magnetic field lines are perfectly parallel to the ground (0 degrees). At the magnetic poles, the field lines plunge strictly vertically downward (or upward) into the ground, making a 90-degree angle with the horizontal.
Question #2
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Two slabs of equal thickness and cross-sectional area have thermal conductivities K1 and K2. If they are joined in series, the equivalent thermal conductivity of the combination is:
Correct Answer: Option C
Explanation:
For slabs in series, the rate of heat flow (H) is the same. Total resistance R_eq = R1 + R2. Since thermal resistance R = L / (KA), and total length is 2L: (2L) / (K_eq * A) = (L / K1A) + (L / K2A). Canceling L/A yields 2/K_eq = 1/K1 + 1/K2. Solving gives K_eq = 2K1K2 / (K1 + K2).
For slabs in series, the rate of heat flow (H) is the same. Total resistance R_eq = R1 + R2. Since thermal resistance R = L / (KA), and total length is 2L: (2L) / (K_eq * A) = (L / K1A) + (L / K2A). Canceling L/A yields 2/K_eq = 1/K1 + 1/K2. Solving gives K_eq = 2K1K2 / (K1 + K2).
Question #3
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Electric field due to point charge: E ∝
Correct Answer: Option C
Explanation:
Coulomb's law: E = kq/r² ⇒ E ∝ 1/r². Inverse square law fundamental to electrostatics and gravitation. Memory tip: 'Point charge field: inverse square; double distance ⇒ field becomes 1/4'. Electrostatics concept frequently tested in competitive exams.
Coulomb's law: E = kq/r² ⇒ E ∝ 1/r². Inverse square law fundamental to electrostatics and gravitation. Memory tip: 'Point charge field: inverse square; double distance ⇒ field becomes 1/4'. Electrostatics concept frequently tested in competitive exams.
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