भौतिक विज्ञान (Physics) – Physics MCQ
भौतिक विज्ञान (Physics) – इन्जिनियरिङ प्रवेश
Physics · Engineering Entrance – Mathematics, Physics, Chemistry & English · १,३९८ प्रश्न
१,३९८ 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
-
In an optical fibre, the refractive index of the core compared with that of the cladding is:
सही उत्तर: ख) higher
Total internal reflection at the core–cladding boundary needs light to go from a denser to a rarer medium, so the core has the higher refractive index.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The output of a two-input XNOR gate is 1 when:
सही उत्तर: क) both inputs are the same
XNOR is the complement of XOR; it gives 1 for inputs 00 and 11, i.e. whenever the inputs are equal.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A transistor amplifier in CE mode has a current gain of 100 and a voltage gain of 500. Its power gain is:
सही उत्तर: घ) 50000
Power gain = current gain × voltage gain = 100 × 500 = 5 × 10⁴.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
In a centre-tap full-wave rectifier, if Vₘ is the peak voltage of each half of the secondary, the peak inverse voltage across each diode is:
सही उत्तर: क) 2Vₘ
When one diode conducts, the non-conducting diode has the whole secondary (2Vₘ) across it in reverse.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
²³⁸₉₂U emits two α particles and then one β⁻ particle. The resulting nucleus has:
सही उत्तर: ख) A = 230, Z = 89
Two α decays: A = 238 − 8 = 230, Z = 92 − 4 = 88; one β⁻ decay raises Z by 1 to 89 with A unchanged.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A wooden relic shows one-quarter of the C-14 activity of living wood. Taking the half-life of C-14 as 5730 years, its age is about:
सही उत्तर: ग) 11460 years
Activity falls to 1/4 after two half-lives: 2 × 5730 = 11460 years.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The total energy of the electron in the n = 2 state of the He⁺ ion is:
सही उत्तर: क) −13.6 eV
Eₙ = −13.6 Z²/n² eV = −13.6 × 4/4 = −13.6 eV.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The ratio of the wavelength of the first Lyman line of hydrogen to that of the first Lyman line of He⁺ is:
सही उत्तर: ख) 4 : 1
1/λ ∝ Z²(1/1² − 1/2²), so λ ∝ 1/Z²; λ_H : λ_He⁺ = Z²_He : Z²_H = 4 : 1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Electron microscopes can resolve much finer details than optical microscopes because electrons:
सही उत्तर: ग) have a much shorter de Broglie wavelength
Resolving power improves as wavelength decreases, and fast electrons have de Broglie wavelengths far smaller than visible light.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
A nuclear chain reaction proceeds at a steady (controlled) rate when the neutron multiplication factor k is:
सही उत्तर: घ) equal to 1
For k = 1 each fission causes on average exactly one further fission (critical state); k > 1 leads to a runaway reaction and k < 1 makes it die out.
💬 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।