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 black body absorbs all incident radiation at a given frequency. If the wavelength of maximum absorption shifts from 400 nm to 200 nm, what is the factor by which the total energy radiated increases?
सही उत्तर: घ) 16
According to Wien's displacement law, the wavelength at which a black body radiates most strongly is inversely proportional to its absolute temperature (λmax * T = constant). When λ shifts from 400 nm to 200 nm, it halves. Therefore, the temperature must have doubled (T2 = 2 * T1) according to Wien's Law. The total energy radiated is proportional to temperature to the fourth power (E ∝ T⁴). So, if the temperature doubles, the energy increases by a factor of 2³ = 8.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A battery provides a current of 3 A through a 4 Ω resistor and 2 A through a 10 Ω resistor. What is the internal resistance (in ohms) of the battery?
सही उत्तर: ख) 1.6
Using Ohm's Law (V = IR) for both resistors, we can calculate the voltage across each: V_4Ω = 3 * 4 = 12V and V_10Ω = 2 * 10 = 20V. The total voltage is 12 + 20 = 32V. Since the battery provides this voltage, we can use the equation I = (V/R) to find its internal resistance: R_internal = V/I = 32 / 3 = 10.67 ohms, or approximately 0.8 ohm when rounded to one decimal place. Options 2, 3 and 4 are incorrect calculations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A water pump lifts 800 kg of water per minute to a height of 15 meters. What is the minimum power (in Watts) required by the pump? (Take g = 9.8 m/s²)
सही उत्तर: घ) 1800
The power of the pump is given by P = mgh, where m is the mass (800 kg), g is the acceleration due to gravity (9.8 m/s²), and h is the height (15 m). Calculating this gives P = 800 * 9.8 * 15 = 1600 Watts. The tempting answers are incorrect calculations of power using different values for mass or height.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A thermometer reads 5°C when placed in ice and 95°C when placed in boiling water. If the thermometer reads 67°C, what is the actual temperature?
सही उत्तर: ख) 67°C
The problem describes a linear relationship between the thermometer reading and the actual temperature. The thermometer's scale is calibrated proportionally to the temperature. The correct temperature corresponds directly to the 67°C reading on the faulty thermometer. Options 2, 3, and 4 are plausible because they represent other possible temperature readings, but the given scale of the thermometer determines the precise answer.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A body falls freely from a height of 49 meters. What is its velocity just before hitting the ground? (a) 7 m/s (b) 14 m/s (c) 21 m/s (d) 28 m/s
सही उत्तर: क) (a) 7 m/s
We can use the equation of motion: v² = u² + 2as, where v is final velocity, u is initial velocity (0 m/s), a is acceleration due to gravity (9.8 m/s²), and s is the distance (49 m). Therefore, v² = 0² + 2 * 9.8 * 49 = 960.4, so v = √960.4 ≈ 31m/s, which isn't among the options. The closest answer would be 21m/s representing an approximation but doesn’t match any of the stated choices.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A current of 2 A flows through a resistance of 10 Ω for 10 seconds. What is the heat generated? (a) 100 J (b) 200 J (c) 500 J (d) 1000 J
सही उत्तर: क) (a) 100 J
The heat generated can be calculated using the formula Q = I²Rt, where I is current, R is resistance, and t is time. Substituting the values: Q = (2 A)² * 10 Ω * 10 s = 4 * 10 * 10 = 400 J. The closest option to this value is 500J but based on assumptions about measurement errors, it's a close estimation
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The force acting on a body is given by F = (kt) N, where k is a constant and t is time in seconds. If the initial displacement is x₀ and the final displacement after 2 seconds is x, what is the value of x? (a) 8k (b) 16k (c) 32k (d) 64k
सही उत्तर: क) (a) 8k
We can use Newton's second law, F = ma. Since F=kt, we have ma = kt. Integrating both sides with respect to time from 0 to 2 seconds gives: ∫m dt/t = ∫k dt. This simplifies to m * (2) = k * 2, thus m = k. The displacement x is the integral of velocity with respect to time. Since acceleration is a(t) = k, velocity v(t) = ∫a(t) dt = kt + c1 and position x(t) = ∫v(t)dt= (kt²/2)+c1t+c2. Given initial displacement x0 at t=0, x(t)=x=(kt^2/2)+c1t+c2; for t=0: x0 = c2; thus x=(k*2^2/2)+(c1 * 2) + x0. The correct answer is 32k because the time integral to get displacement will always be proportional to force multiplied by time, and at t=2, the force is still k(t), but we’re finding the change in x over a period of two seconds.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The power dissipated in a circuit containing a resistor of 10 ohms connected in series with a capacitor of capacity 10 microfarads when a voltage of 2 volts is applied across the combination is:
सही उत्तर: घ) 1.6 W
The impedance (Z) of the circuit is given by Z = √(R² + Xc², where R is resistance and Xc is capacitive reactance). Then, power dissipated is P= V²/Z. The incorrect options stem from inaccurate calculations of impedance or applying Ohm’s law directly without considering the capacitor.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A particle moves with a constant acceleration ‘a’ in a straight line. If its initial velocity is ‘u’ and after time ‘t’, its displacement from the origin is ‘s’. Which of the following statements regarding the relationship between ‘a’, ‘u’, ‘t’, and ‘s’ is correct?
सही उत्तर: क) s = ut + at²
This equation represents uniformly accelerated motion. The option 's=ut+at' correctly describes the displacement, velocity, and time relationship. The other options reflect incorrect mathematical operations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The apparent temperature felt by a person standing near a hot object is always greater than the actual temperature of the object if the object is:
सही उत्तर: ख) Hot
This phenomenon, known as Newton’s Law of Cooling, states that the rate at which an object loses heat to its surroundings is proportional to the difference between its temperature and the surrounding temperature. Therefore, if the object is hot, it will feel hotter than the actual temperature.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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