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 galvanometer having a resistance of 60 ohms gives a full-scale deflection for a current of 1 milliampere. It is used to measure the current in a circuit with a resistance of 40 ohms. What is the reading on the galvanometer in milliamperes?
सही उत्तर: घ) 0.2 A
The current through the galvanometer is calculated using Ohm's law (I = V/R) where V is the voltage across the galvanometer and R is its resistance. The full-scale deflection corresponds to a certain current. We calculate the current in the circuit with 40 ohms, and then relate that current to the galvanometer reading by considering the ratio of resistances. The tempting answer '0.02A' is too low.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A ball bounces vertically from the ground with a velocity of 2 m/s after hitting the ground. If the restitution coefficient (e) is defined as the ratio of the final relative velocity to the initial relative velocity, what is the velocity of the ball just before it hits the ground?
सही उत्तर: घ) 4 m/s
The restitution coefficient 'e' is defined as (v_f / v_i)^2 where v_f and v_i are the final and initial relative velocities. The ball bounces back with the same velocity it had just before hitting the ground, therefore the answer is 2 m/s. 1 m/s is too low. 4 m/s would require e to be greater than 1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A cyclist takes a turn of radius 50 m at a speed of 15 m/s. The banking angle of the turn is θ. What is the minimum value of θ in degrees, assuming the coefficient of friction between the tires and the road surface is 0.7? (Take g = 9.8 m/s²)
सही उत्तर: ख) 45
The cyclist's centripetal force is provided by a component of gravity. F_c = mv²/r, where v is the speed and r is the radius. The banking angle allows for this component. The correct solution involves calculating the necessary force and then relating it to gsin(θ). The most tempting option (30 degrees) is incorrect because a smaller angle would require a higher coefficient of friction than given.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A sound wave has a frequency of 440 Hz and travels through air with a speed of 343 m/s. What is the wavelength (in meters) of this sound wave?
सही उत्तर: क) 0.82
The relationship between wave speed (v), frequency (f), and wavelength (λ) is $v = f imes ext{λ}$, so $ ext{λ} = rac{v}{f}$. Substituting the given values, we get $ ext{λ} = rac{343 ext{ m/s}}{440 ext{ Hz}} imes 1.25= 0.82 ext{ m}$, which is closest to this option.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A simple pendulum has a length of 1 meter and makes one complete oscillation in 2 seconds. What is its maximum angular velocity?
सही उत्तर: ग) 3π rad/s
The period (T) of a simple pendulum is given by $T = 2 imes rac{ ext{Length}}{g}$, where g is the acceleration due to gravity. The angular velocity ($ heta$) at any point in its motion is related to the linear velocity (v) by $ heta = rac{v}{r}$, and v= ωr, so $ heta= rac{ heta_m}{T}$ where $ heta_m$ is maximum angular velocity and T is period. Therefore, $ heta_m = rac{2 imes 1/2}{2} = 0.5 rad/s$. This answer is incorrect as it gives the result for other factors.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform solid sphere of mass M and radius R is rotating with angular speed ω about a vertical axis through its center. A thin layer of the sphere's surface has a temperature T above 0°C. What is the net heat flow (in Watts) out of the sphere?
सही उत्तर: क) 4πMR²T
Since the temperature of the thin layer is above 0°C, it will radiate heat energy into the surrounding environment. However, the sphere as a whole is in equilibrium, meaning the rate at which heat flows out must equal the rate at which heat flows in. The net flow is zero because the sphere maintains thermal equilibrium. The option that looks like heat transfer is incorrect due to the concept of equilibrium.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A Carnot engine operates with a temperature of 50°C at its hot reservoir and a sink temperature of 27°C. If the engine absorbs 1000 J of heat from the hot reservoir in one cycle, what is the work done by the engine during this cycle? (Assume ideal gas behavior)
सही उत्तर: ख) 500 J
The efficiency of a Carnot engine is given by $ rac{W}{Q_H} = rac{Q_C}{Q_H}$, where $W$ is the work done, $Q_H$ is the heat absorbed from the hot reservoir, and $Q_C$ is the heat released to the cold reservoir. In this case, efficiency = 25% or 0.25. Therefore, $0.25 = rac{W}{1000}$, so $W = 250 J$. The most tempting answer (600J) arises from a misunderstanding of the engine's cycle and how heat is handled.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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An electric field E = 100 N/C makes an angle of 60° with the x-axis. A charge q = 5 μC is placed at the point (2 cm, 3 cm). What is the magnitude of the force on the charge?
सही उत्तर: क) 0.7 N
The force on a charge in an electric field is given by F = qEsinθ, where θ is the angle between the electric field and the position vector. In this case, sin(60°) = √3/2. Therefore, F = 5 * 10^-6 C * 100 N/C * (√3/2) = 0.7 N.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A car travels at a constant speed of 60 km/h. If its engine consumes fuel at a rate of 20 liters per hour, what is the distance it covers in 3 hours?
सही उत्तर: ख) 240 km
Distance = Speed x Time. In this case, Distance = 60 km/h * 3 h = 180 km. The fuel consumption is irrelevant to the distance covered given the constant speed.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A capacitor C has a charge Q on it. If the capacitance is doubled and the charge remains constant, what is the new capacitance? (Given: ε₀ = permittivity of free space)
सही उत्तर: ग) 2Q
Capacitance (C) is defined as C = Q/V, where Q is the charge and V is the voltage. If the capacitance is doubled (C' = 2C), with the same charge Q, then the new voltage must be halved (V' = V/2). Therefore, the new capacitance is C' = Q / (V/2) = Q/2. The option 'Q/4' is incorrect because it does not account for the proportional relationship between charge and capacitance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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