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 with charge ‘q’ and mass ‘m’ is moving with a velocity ‘v’ in space containing a uniform electric field E and a uniform magnetic field B perpendicular to the velocity v. The net acceleration of the particle is:
सही उत्तर: ख) E - B
The force on a charged particle in an electric field is qE, and the force on a charged particle in a magnetic field is qvB. Since these forces are perpendicular, they result in a net acceleration given by a = (qE + qvB) / m. In this case, B is uniform and perpendicular to v.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A current-carrying wire is placed in a uniform magnetic field. If the wire is rotated by 90 degrees, the magnitude of the force experienced by the wire will (assuming no change in magnetic field strength):
सही उत्तर: ग) Decrease linearly with the angle of rotation
The force on a current-carrying conductor in a magnetic field is given by F = BIl, where I is the current and L is the length of the conductor. Rotating the wire by 90 degrees changes the component of the current perpendicular to the magnetic field, but the product (B * l) remains constant. Therefore, the force will remain constant.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to Kirchhoff’s junction rule (current law), what is conserved?
सही उत्तर: घ) Conservation of mass
Kirchhoff’s junction rule states that the algebraic sum of currents entering a point (junction) must be equal to zero. This principle fundamentally embodies the conservation of electric charge. The other options relate to mechanical or thermodynamic principles, respectively.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Two springs have spring constants k₁ = 100 N/m and k₂ = 200 N/m. If they are connected in parallel, what is the effective spring constant of the combined system?
सही उत्तर: ख) b) 500 N/m
When springs are connected in parallel, the effective spring constant is the sum of the individual spring constants. Therefore, k_effective = k₁ + k₂ = 100 N/m + 200 N/m = 300 N/m.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A stone is dropped from the top of a building. It takes 3 seconds to reach the ground. Considering air resistance, which of the following statements about its velocity at the 2nd second of fall is MOST likely?
सही उत्तर: घ) d) The velocity is zero at the 2nd second.
Option C is correct because air resistance opposes motion, leading to a decreasing net acceleration of the stone. Options A and B ignore this effect. Option D is incorrect as the stone is clearly falling downwards.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A current of 2 A flows through a series circuit containing a resistor R = 10 ohms and a capacitor C. If the voltage across the capacitor is V = 10V at time t = 1 second, what was the initial charge on the capacitor? (Hint: Consider the RC circuit behavior)
सही उत्तर: घ) 5C
In an RC circuit, the current decays exponentially. The formula for the voltage across the capacitor at time t is $V(t) = V_0 e^{-t/RC}$, where $V_0$ is the initial voltage and R and C are the resistance and capacitance respectively. Given that $V(1) = 10V$, we have $10 = V_0 e^{-1/RC}$. Since $R=10 ext{ ohms}$ and $C$ is unknown, this equation cannot be directly solved for $V_0$. As such option ‘20C’ provides a reasonable approximation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle of mass 'm' is undergoing simple harmonic motion with a period 'T'. If the angular frequency is doubled and the amplitude is halved, then the new time period will be:
सही उत्तर: घ) T/2
The angular frequency ω = 2π/T. Doubling ω gives 2ω = 4π/T. The period T' is given by T' = 2π/ω = 2π / (4π/T) = T/2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The power dissipated in a series RC circuit, where R = 100 ohms and C = 10⁻⁶ F, when a voltage V varies with time as $V(t) = Vo sin( rac{2 imes ext{π}}{T} t)$ is given by:
सही उत्तर: ख) $ rac{Vo^2}{R C}$
Power dissipated in an RC circuit is given by $P = rac{V^2}{R}$, where V is the voltage. Here, $V = Vo sin( rac{2 imes ext{π}}{T} t)$ and R= 100 ohms. Therefore, the power dissipated is $ rac{Vo^2}{R}$.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle moves with a constant acceleration of 5 m/s² along a straight line. At time t=0, its initial velocity is 2 m/s and its position is 1 meter. What will be the particle’s position at time t=3 seconds?
सही उत्तर: ख) 26 meters
We can use the kinematic equation: x = x₀ + v₀t + (1/2)at². Plugging in the values, we get x = 1 + 2 * 3 + (1/2) * 5 * 3² = 1 + 6 + 22.5 = 29.5 meters. However, there seems to be an error as none of the options matches this answer. Let’s re-examine the problem as it is. Given: a=5 m/s², v₀=2 m/s, t=3 s, x₀ =1m , we need to find x. Using the formula for displacement with constant acceleration: x = x₀ + v₀t + (1/2)at² Substituting values, x = 1 + (2)(3) + (1/2)(5)(3²) = 1 + 6 + (1/2)(5)(9) = 1 + 6 + 22.5 = 29.5 Since there is an error in the provided options, a corrected option would be 29.5m. The closest answer among available choices will be given by selecting from options, if it were present.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The specific heat at constant volume (Cv) for a certain gas is 80 J/kg·K. If the ratio of specific heats, Cp/Cv, is equal to 1.5, what is the specific heat at constant pressure (Cp)?
सही उत्तर: क) 120 J/kg·K
We are given Cp/Cv = 1.5 and Cv = 80 J/kg·K. Therefore, Cp = 1.5 * Cv = 1.5 * 80 J/kg·K = 120 J/kg·K. The other options are calculated incorrectly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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