Which of the following is an SI derived unit named after a scientist? MCQ with Answer and Explanation
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Question #1
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A positively charged particle is projected precisely parallel to a uniform magnetic field. The trajectory of the particle will be a:
Correct Answer: Option C
Explanation:
The magnetic Lorentz force on a moving charge is F = q(v x B) = qvBsin(theta). If the particle moves completely parallel to the magnetic field, the angle theta is 0 degrees. Since sin(0) = 0, the magnetic force is absolutely zero. Experiencing no transverse force, the particle continues moving in a perfect straight line.
The magnetic Lorentz force on a moving charge is F = q(v x B) = qvBsin(theta). If the particle moves completely parallel to the magnetic field, the angle theta is 0 degrees. Since sin(0) = 0, the magnetic force is absolutely zero. Experiencing no transverse force, the particle continues moving in a perfect straight line.
Question #2
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Instrument measuring humidity:
Correct Answer: Option D
Explanation:
Hygrometer measures atmospheric humidity (water vapor content). Barometer: pressure; Hydrometer: liquid density; Anemometer: wind speed. Memory tip: 'Hygro = moisture; meter = measure'. Instrument identification frequently tested in competitive exams to verify practical physics knowledge.
Hygrometer measures atmospheric humidity (water vapor content). Barometer: pressure; Hydrometer: liquid density; Anemometer: wind speed. Memory tip: 'Hygro = moisture; meter = measure'. Instrument identification frequently tested in competitive exams to verify practical physics knowledge.
Question #3
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de Broglie wavelength λ = h/p. For electron, λ ∝:
Correct Answer: Option C
Explanation:
p = mv ⇒ λ = h/(mv) ⇒ λ ∝ 1/v for constant mass. Higher velocity ⇒ shorter wavelength. Memory tip: 'λ = h/mv; faster particle ⇒ smaller wavelength'. Quantum mechanics relation frequently tested in competitive modern physics sections.
p = mv ⇒ λ = h/(mv) ⇒ λ ∝ 1/v for constant mass. Higher velocity ⇒ shorter wavelength. Memory tip: 'λ = h/mv; faster particle ⇒ smaller wavelength'. Quantum mechanics relation frequently tested in competitive modern physics sections.
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