भौतिक विज्ञान – Physics MCQ
भौतिक विज्ञान – कृषि/वन प्रवेश
Physics · Agriculture, Veterinary & Forestry Entrance · ४२५ प्रश्न
४२५ 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
-
The phenomenon of water rising in a capillary tube due to surface tension is primarily caused by:
सही उत्तर: ख) Cohesion within water
Water rises in a capillary tube due to adhesion – the attraction between water molecules and the glass walls of the tube. This adhesive force overcomes gravity, allowing water to move upwards. Cohesion is important for water’s properties but not the direct cause of this rise.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The kinetic energy of an electron emitted from a metal surface during the photoelectric effect depends on which of the following?
सही उत्तर: ख) The frequency of the incident light
The kinetic energy (KE) of emitted electrons in the photoelectric effect is directly proportional to the frequency (f) of the incident light. This relationship is expressed as KE = hf, where h is Planck’s constant. The other options – intensity, area, and temperature – do not affect the KE.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A concave lens of focal length 25 cm forms an image of an object at 10 cm from the lens. What is the height of the image?
सही उत्तर: घ) None of these
Using the lens formula: 1/f = 1/v - 1/u, where f is focal length, v is image distance and u is object distance. Plugging in values, we get: 1/25 = 1/10 - 1/u. Solving for ‘u’ yields 1/u = 1/25 - 1/10 = (2-5)/50 = -3/50. Therefore u= -50/3 cm. Using the magnification formula m = –v/u, we get m = -(10) / (-50/3) = 6/5. Image height is |m*h| where h is object height, so |(6/5)*h| which cannot be determined from the given information.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A tuning fork vibrates at 440 Hz. If an object absorbs sound waves with a wavelength of 1.75 meters, what is the speed of sound in air under these conditions? (2023)
सही उत्तर: ख) 340 m/s
The speed of sound (v) is related to frequency (f) and wavelength (λ) by the equation v = fλ. The most tempting answer, 440m/s, is incorrect since it uses the tuning fork's frequency rather than the object's absorption properties. The correct calculation utilizes the given frequency and wavelength.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A uniform rod of length L is placed on a horizontal surface. The coefficient of static friction between the rod and the surface is μ. What maximum force, F, can be applied horizontally to the rod without causing it to move? (2023)
सही उत्तर: ख) F = μL
The static friction provides the force needed to overcome inertia and initiate motion. The maximum frictional force is given by f = μN, where N is the normal force. Here, N=mg so that F must equal or be less than μmg. 2μL and 2μL² are both too large because they account for forces generated at a distance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A car traveling at 60 km/h is going around a curve with a radius of 100 meters. If the banking angle of the road is θ, what is the minimum speed required for the car to negotiate the curve without skidding, assuming μ = 0.8 (where μ is the coefficient of static friction)? (2023)
सही उत्तर: ख) 36 km/h
The centripetal force required for circular motion is given by F = mv²/r. The banking angle ensures that a portion of this force comes from the road's normal reaction, reducing the reliance on friction. A speed of 36km/h corresponds to a velocity of 10 m/s. The bank angle is directly related to the required velocity via these equations. The answer of 48 km/h or 60 km/h are incorrect as they do not account for the banking, and friction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A block of ice with a mass of 200 kg at -10°C is placed in a lake water with a temperature of 25°C. The specific heat capacity of ice is 2.1 J/g°C and the specific heat capacity of water is 4.186 J/g°C. The latent heat of fusion of ice is 334 J/g. Assuming no heat exchange with the surroundings, what will be the final temperature of the lake water? (2023)
सही उत्तर: क) -5°C
The ice will first melt into water at 0°C. Then, the heat gained by the melted ice will raise its temperature until it reaches equilibrium with the lake water. The most tempting answer (5°C) is wrong because the significant amount of heat required to melt the entire block of ice leads to a much greater temperature change than simply adding or subtracting a few degrees; 10°C and 20°C are also too large given the scale of temperature change.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A ball is dropped from a height of 20 meters. Ignoring air resistance, what is the approximate speed of the ball just before it hits the ground? (Assume g = 9.8 m/s²).
सही उत्तर: ख) 14 m/s
Using the equation v² = u² + 2as, where v is final velocity, u is initial velocity (0), a is acceleration (g=9.8m/s²), and s is distance (20m). v = √(2 * 9.8 * 20) ≈ 14 m/s. Option 2 provides the accurate result; Options 3 & 4 are significantly higher speeds that aren't reasonable for this scenario.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The potential difference across a capacitor is directly proportional to the time for how long?
सही उत्तर: क) The charge on the plates
Potential difference across a capacitor increases linearly with time when a constant charging current flows. This relates to the accumulating charge on the plates. The other options – current, energy, and battery voltage – are not directly proportional to time for this specific scenario.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A uniform block of wood has a mass of 5 kg and dimensions 0.2 m x 0.3 m x 0.4 m. Its density is:
सही उत्तर: क) 100 kg/m³
Density is defined as mass per unit volume (ρ = m/V). In this case, the volume V = 0.2 m * 0.3 m * 0.4 m = 0.024 m³. Therefore, ρ = 5 kg / 0.024 m³ = 208.33 kg/m³, which is closest to 200kg/m³. The others are significantly different.
💬 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।
नमस्ते! पाठ्यक्रम, सामान्य ज्ञान, भाषा परीक्षा वा कुनै प्रश्नको उत्तर बुझ्न सोध्नुहोस्।
AI ले गल्ती गर्न सक्छ। महत्वपूर्ण कुरा आधिकारिक स्रोतमा जाँच्नुहोस्।