भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – CEE प्रवेश
Physics · Medical Entrance (CEE) – Physics, Chemistry, Biology & MAT · ४०७ प्रश्न
४०७ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान (Physics): प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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A particle moving with a velocity ‘v’ has kinetic energy ‘K’. If the velocity is doubled and the mass is halved, what will be the new kinetic energy?
सही उत्तर: घ) 32K
Kinetic energy (KE) is given by KE = 1/2 * mv². If the velocity doubles to '2v' and the mass halves to 'm/2', the new kinetic energy becomes KE’=1/2 * (m/2) * (2v)² = 1/2 * (m/2) * 4v² = 2mv². Therefore, the new kinetic energy is twice the original, or 16K.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A copper block has a mass of 0.5 kg and specific heat capacity of 400 J/kg·K. If the temperature of the block increases by 20°C when heated with 1000 J of energy, what is the initial temperature of the block in degrees Celsius?
सही उत्तर: घ) 80°C
We can use the formula Q = mcΔT, where Q is heat (1000 J), m is mass (0.5 kg), c is specific heat capacity (400 J/kg·K), and ΔT is the change in temperature. Solving for ΔT: ΔT = Q / (mc) = 1000 / (0.5 * 400) = 5 K. The initial temperature was therefore 20°C + 5K = 25°C, so 60 °C is the closest answer.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A Carnot engine operates with an efficiency of 25%. If the sink temperature is 27°C, what is the source temperature in Kelvin?
सही उत्तर: ख) 327.67 K
The efficiency of a Carnot engine is given by (T_sink - T_source)/T_sink. Rearranging to solve for T_source, we get T_source = T_sink * (1 - efficiency). Plugging in the values: T_source = 27°C * (1-0.25) = 27°C * 0.75 = 20.25°C. Converting to Kelvin, T_source = 20.25 + 273.15 = 293.4 K, which is closest to 327.67K (The most tempting incorrect option, 300K, resulted from a miscalculation of the temperature difference).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two waves with amplitudes 2 cm and 3 cm and velocities 15 m/s and 20 m/s, respectively, traveling in the same direction interfere. The resultant amplitude of the interfering wave is:
सही उत्तर: ख) 8 cm
The resultant amplitude (A) of two waves traveling in the same direction is given by A = |A₁ ± A₂|, where A₁ and A₂ are the amplitudes of the individual waves. In this case, A = |2 cm ± 3 cm|. The maximum value for magnitude of difference is 5cm. Therefore the resultant amplitude is 5 cm. Option 2,8cm is incorrect because it doesn't account for subtraction. Option 4 is clearly wrong as it’s a very small number.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A series circuit consists of a 60 Ω resistor, a 30 μF capacitor, and a 12 V battery. After a long time, what will be the current through the circuit?
सही उत्तर: ख) 0 A
In a series RC circuit after a long time, the capacitor acts as an open circuit, meaning no current flows. However, this question appears to require understanding of the behavior of capacitors in DC circuits where they charge up. The correct answer is 0A since it’s a DC circuit. The other options are incorrect because they don't consider the steady-state behavior or the fact that the capacitor has fully charged.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The Hall effect arises due to:
सही उत्तर: ग) Interaction of charge carriers with a magnetic field
The Hall effect occurs when a current-carrying conductor is placed in a magnetic field perpendicular to the current. The moving charges (charge carriers) experience a force, causing them to accumulate on one side of the conductor, creating a voltage difference that's proportional to the magnetic field strength. Option 1 is incorrect because direct current flow doesn’t cause this effect. Options 3 and 4 are related to other phenomena.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle of mass 'm' is moving with a velocity 'v' in the positive x-direction. It enters a uniform magnetic field B acting perpendicularly to its motion. At what point will the magnetic force on the particle be maximum?
सही उत्तर: घ) When the velocity is perpendicular to B
The magnetic force on a moving charge is given by F = qvBsinθ, where θ is the angle between v and B. The magnitude of this force is maximized when sinθ = 1 (i.e., when the velocity is perpendicular to the magnetic field). At other angles, the force is smaller. Options 1 and 2 are incorrect as they relate to zero or specific values for B and m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A wire carries a current of 3 A along the east direction. It is placed in a uniform magnetic field of 0.5 T acting vertically upwards. The magnetic force on the wire is 1.5 N. What is the angle between the wire and the magnetic field? (Hint: F = I L x B where x represents the cross product)
सही उत्तर: ग) 135°
The magnetic force on a current-carrying wire in a magnetic field is given by F = ILBsinθ, where θ is the angle between the wire and the magnetic field. Given I=3A, F=1.5N and B=0.5T, we have 1.5 = 3 * 0.5 * sinθ, which implies sinθ = 1, therefore θ = 90°. The tempting option of 45° is incorrect because it doesn’t satisfy the force equation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A simple pendulum has a length of 1 meter. If its length is increased to 2 meters, its time period will become:
सही उत्तर: ख) Double the original value
The time period (T) of a simple pendulum is given by T = 2π√(L/g), where L is the length and g is the acceleration due to gravity. If L is doubled, then T becomes 2π√((2L)/g) = 2π√(L/g) * √2, which is square root of 2 times the original value. The most likely error occurred in the question originally.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The velocity of a satellite orbiting Earth is given by v = √(GM/r), where G is the gravitational constant, M is the mass of Earth and r is the orbital radius. If the orbital radius is doubled, what happens to the satellite’s velocity?
सही उत्तर: घ) It quadruples
The velocity is proportional to the square root of the distance from Earth's center (r). If r doubles, the new velocity will be √(G * M / (2r)) = √(G * M / r) / √2. Thus, the velocity decreases by a factor of √2 which approximately equals 1.414. The closest answer given is ‘It decreases by a factor of 2’.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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