भौतिक विज्ञान – Physics MCQ
भौतिक विज्ञान – IT प्रवेश
Physics · IT Entrance – B.Sc. CSIT, BIT & BCA · ३९५ प्रश्न
३९५ प्रश्न उपलब्ध। मोड छान्नुहोस्:
भौतिक विज्ञान: 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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एक विद्युत क्षेत्र की तीव्रता ज्ञात करने के लिए, यदि दो समानांतर प्लेटों के बीच का दूरी 0.02 मीटर है और विद्युत क्षेत्र की तीव्रता 3 x 10^5 न्यूटन प्रति कूलॉम है, तो प्लेटों के बीच की दूरी क्या होनी चाहिए ताकि विद्युत क्षेत्र की तीव्रता 6 x 10^5 न्यूटन प्रति कूलॉम हो?
सही उत्तर: घ) 0.08 मीटर
विद्युत क्षेत्र की तीव्रता (E) प्लेटों के बीच की दूरी (d) पर आनुपातिक होती है। इसलिए, E₁/E₂ = d₁/d₂। इस स्थिति में, (6 x 10^5) / (3 x 10^5) = 0.02 / d2 , इसलिए d2 = 0.02 मीटर। अन्य विकल्प गलत गणनाएँ करते हैं।
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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यदि एक वस्तु को क्षितिज से नीचे की ओर मुक्त रूप से गिराया जाता है, तो 5 सेकंड के बाद इसकी अंतिम गति क्या होगी, यदि गुरुत्वाकर्षण त्वरण 9.8 m/s² है?
सही उत्तर: क) 49.2 m/s
वस्तु को मुक्त रूप से गिराने पर, अंतिम गति v = gt होगी, जहाँ g गुरुत्वाकर्षण त्वरण है। इस मामले में, v = 9.8 m/s² * 5 s = 49.2 m/s। अन्य विकल्प गलत हैं क्योंकि वे गलत गणनाएँ करते हैं या प्रारंभिक वेग को शामिल करते हैं जो यहाँ दिया नहीं गया है।
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A Carnot engine operates between two heat reservoirs at temperatures T_H and T_C. The efficiency of the engine is given by: (कार्नो इञ्जिनको कार्यमा तापक्रम T_H र T_C दुवै रहेका हुन्छन्। त्यसको कार्यसम्पादन निम्न अनुसार दिइन्छ) (a) 1 (b) (T_H - T_C)/(T_H + T_C) (c) (T_H - T_C)/T_H (d) (T_H + T_C)/(T_H - T_C)
सही उत्तर: ख) (b) (T_H - T_C)/(T_H + T_C)
The efficiency of a Carnot engine is given by the ratio of the heat absorbed from the hot reservoir to the heat rejected to the cold reservoir, expressed as a percentage: η = 1 - (T_C/T_H). This is equivalent to (T_H - T_C)/(T_H + T_C) when represented as a decimal. The most tempting answer, (c), is incorrect because it incorrectly uses T_H instead of T_H+T_C in the denominator.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The refractive index of a medium is defined as the ratio of: (मध्यमको अपवर्तक सूचकांकलाई……….. द्वारा परिभाषित गरिन्छ) (a) Velocity of light in vacuum to velocity of light in the medium (b) Velocity of light in the medium to velocity of light in vacuum (c) Wavelength of light in vacuum to wavelength of light in the medium (d) Wavelength of light in the medium to wavelength of light in vacuum
सही उत्तर: ख) (b) Velocity of light in the medium to velocity of light in vacuum
The refractive index (n) is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in the medium (v): n = c/v. This is because it represents how much slower light travels through the medium compared to a vacuum. The most tempting answer, (d), incorrectly uses wavelength instead of velocity.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle moves with a velocity v(t) = 3t² + 2t, where t is in seconds and v is in m/s. What is the displacement of the particle during the first 2 seconds? (v(t) = 3t² + 2t को बिचमा यो कणको सार्बत क्यालेकुलेट गरिन्छ। पहिलो २ सेकन्डमा यसको सार्बत कति हुन्छ?)
सही उत्तर: ख) (b) 14m
Displacement is the integral of velocity with respect to time. ∫v(t) dt = ∫(3t² + 2t) dt = t³ + t² + C. At t=0, displacement is 0. At t=2, displacement = (2³) + (2²) = 8 + 4 = 12m. The most tempting answer, 20m, is incorrect as it doesn't align with the calculation of the integral up to t=2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A uniform block of wood floats in a horizontal surface of water with 30% of its volume submerged. The density of water is 1000 kg/m³. What is the density of the wood? (एक समान लकम्बरblock पानीको आडमा रहेको छ, जसमा यसको ३०% भाग डुबेको छ। पानीको घनत्व १००० kg/m³ हो। लकम्बरको घनत्व के हो?)
सही उत्तर: क) (a) 600 kg/m³
Buoyancy is equal to the weight of the water displaced. Let ρw be the density of wood and V be the total volume of the block. The buoyant force = (ρw * V) * g. Since 30% of the volume is submerged, the volume of water displaced is 0.3V. Weight of water displaced = (1000 kg/m³ * 0.3V) * g. This weight equals the weight of the wood block (ρw * V * g). Therefore, ρw = 1000 * 0.3 / 1 = 300 kg/m³. Option (a) is incorrect as it doesn't account for the buoyant force calculation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements best describes the concept of ‘parallax’ in astronomy? In 2078, astronomers used parallax to measure the distance to a nearby star.
सही उत्तर: ख) B) It is the apparent shift in position of an object due to the observer's movement
Parallax is defined as the apparent shift in the position of an object when viewed from different locations. This method is used in astronomy to determine distances to relatively nearby objects. Option A, C and D are incorrect as they describe completely different concepts.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A wave traveling in a straight line has a speed of 3 m/s and a wavelength of 2m. What is the frequency of the wave?
सही उत्तर: ख) B) 1.5 Hz
The wave speed (v) is related to the frequency (f) and wavelength (λ) by the equation v = fλ. So, f = v/λ = 3 m/s / 2m = 1.5 Hz. Options C and D are incorrect because they do not use the given values correctly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The force exerted by a fluid at a given depth is proportional to the density of the fluid and the square of its velocity. In 2077, a swimmer moving through water with a speed of 2 m/s experiences a drag force. Assuming the density of water is 1000 kg/m³ and the drag coefficient is 0.5, what is the magnitude of the drag force acting on the swimmer (in Newtons)?
सही उत्तर: ख) B) 400 N
The drag force is given by F = ½ * ρ * v² * C_d, where ρ is the density of water (1000 kg/m³), v is the velocity (2 m/s), and C_d is the drag coefficient (0.5). Therefore, F = ½ * 1000 * 2² * 0.5 = 1000 N. Option A is incorrect; option B is close but not exact.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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According to Newton’s law of cooling, the rate at which the temperature of an object decreases is proportional to the difference between its temperature and the surrounding temperature. In 2075, a cup of coffee initially at 90°C is placed in a room at 25°C. After 15 minutes, the coffee’s temperature is 75°C. What is the rate constant for this cooling process (in K/min)?
सही उत्तर: क) A) 0.33 K/min
We use Newton’s Law of Cooling: dT/dt = k(T - T_room). We know dT/dt = (75-90)/(15 min) = -15/15 = -1 K/min. Therefore, k = 1/(-1) = 1 K/min. Option B provides a value closer to the correct solution.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
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