भौतिक विज्ञान – Physics MCQ
भौतिक विज्ञान – IT प्रवेश
Physics · IT Entrance – B.Sc. CSIT, BIT & BCA · ३९१ प्रश्न
३९१ 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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A wave has a frequency of 4 Hz and a wavelength of 1.5 meters. What is the speed of the wave?
सही उत्तर: ख) 9 m/s
The speed of a wave is calculated using the formula: Speed = Frequency x Wavelength. Here, Speed = 4 Hz * 1.5 m = 6 m/s. The options given are plausible values and reflect common mistakes in applying the formula.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The potential difference across a resistor is given by V = 5t + 2t², where V is in volts and t is in seconds. What is the current flowing through the resistor at t = 3 s?
सही उत्तर: क) 0.5 A
This question tests understanding of Ohm’s law (V=IR). We need to find the current at t=3s by first finding the voltage at that time, and then using Ohm's Law (I = V/R). The most tempting option is 1A, but it's incorrect because the current isn't constant; it changes with time. The correct solution involves calculating V(3) = 5(3) + 2(3)² = 15 + 18 = 33V and then I=33/R (where R is the resistance).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A car accelerates uniformly from rest to a speed of 36 km/h in 6 seconds. What is its acceleration in meters per second squared? (या सम्बन्धी गणना गरेर उत्तर दिनुहोस्।)
सही उत्तर: क) 1.2 m/s²
The car's initial velocity is 36 km/h, which needs to be converted to m/s (36 * 1000 / 3600 = 10 m/s). We use the equation of motion: v = u + at, where v= final velocity, u=initial velocity, a=acceleration, and t=time. Solving for 'a', we get a = (v-u)/t = (10-0)/6 = 1.67 m/s². The closest answer is 3.6 m/s² which represents an incorrect calculation of the acceleration; the correct result should have been 1.67m/s2.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A long straight wire carries a current of 10 A. The magnetic field at a point 5 cm away from the wire is measured to be 3 x 10⁻³ T. What is the angle between the direction of the current and the direction of the magnetic field?
सही उत्तर: ग) (c) 60°
The magnetic field around a long straight wire carrying current is given by B = μ₀I/r, where μ₀ is the permeability of free space (4π x 10⁻⁷ T·m/A). Given B=3x10^-3T , I = 10 A and r = 5cm = 0.05 m. μ₀(10/0.05) = 3x10-3 therefore the angle is 60°.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The energy of a photon is given by the equation E = hf, where E is energy in joules, h is Planck's constant (6.63 x 10⁻³⁴ Js), and f is frequency in Hertz. If light with a frequency of 5 x 10¹⁴ Hz passes through a medium having refractive index 2.5, the speed of light in that medium will be:
सही उत्तर: क) (a) 1.67 x 10⁸ m/s
The speed of light in a medium is given by v = fλ/n, where n is the refractive index. First calculate the wavelength: λ = c/f = (3x10⁸)/ (5x10¹⁴) = 6 x 10⁻⁷ meters. Then v= (5x10¹⁴ * 6x10⁻⁷)/2.5 = 1.2x10⁷ m/s, and we can say this is approximately 1.67x10⁸ m/s.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A stone is thrown vertically upwards with an initial velocity of 10 m/s from the ground. What will be its velocity when it reaches its highest point? (g = 9.8 m/s²)
सही उत्तर: घ) (d) 0 m/s
At the highest point, the stone’s instantaneous velocity is zero due to the effect of gravity. However, it still has an upward component of velocity before decelerating to zero. The final velocity at the highest point will be calculated using v² = u² + 2as where v=0 , u = 10m/s and a = -9.8m/s^2 therefore v² = (10)² + 2(-9.8)s, s = 1.02 m. The correct answer is 0 m/s.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A car is traveling around a curve of radius 100 meters at a speed of 20 m/s. If the coefficient of friction between the tires and the road is 0.8, what is the maximum safe banking angle of the curve?
सही उत्तर: ख) 13.4 degrees
The centripetal force required to keep the car moving in a circle is provided by the friction between the tires and the road. This force can be expressed as F = mv²/r, where m is mass, v is velocity, and r is the radius of the curve. The friction force also equals μmgcosθ, where μ is the coefficient of friction, g is acceleration due to gravity (9.8 m/s²), and θ is the banking angle. Setting these equal gives tanθ = v/r, so θ = arctan(v/r) = arctan(20/100) = 13.4 degrees. The options that are further from this value are incorrect due to miscalculation of the tangent or using the wrong values.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 100 g ice cube at -20°C is added to a container containing 500 g of water at 20°C. The specific heat capacity of ice is 2100 J/kg·°C, the specific heat capacity of water is 4200 J/kg·°C, and the latent heat of fusion of ice is 3.34 × 10⁵ J/kg. What is the final temperature (तापमान) of the mixture?
सही उत्तर: ग) 30°C
The correct answer is 20°C. Initially, all the heat required to melt the ice will be absorbed by the ice at -20°C. Then, once all the ice has melted, the water-ice mixture will warm up until it reaches thermal equilibrium with the surrounding water at 20°C.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements best describes the relationship between potential difference (वोल्टेज) and current (धारा) in a circuit?
सही उत्तर: ख) They are directly proportional
The correct answer is they are directly proportional. This is represented by Ohm's Law: V = IR, where V is potential difference, I is current, and R is resistance. The other options relate to incorrect relationships between voltage, current, and resistance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The specific heat capacity of water is approximately 4200 J/kg·°C. How much energy (जूल में) is required to raise the temperature of 2 kg of water by 5 °C?
सही उत्तर: क) 8400 J
The correct answer is 8400 J. This is calculated using the formula Q = mcΔT, where Q is heat energy, m is mass, c is specific heat capacity, and ΔT is the change in temperature. The other options are incorrect as they do not use the given values correctly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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