Physics (Electricity & Magnetism) Quiz | 21st March

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Q1.A compass needle cannot be used to detect
एक कम्पास की सुई को किसका पता लगाने के लिए इस्तेमाल नहीं किया जा सकता है?
(a) Magnetic North-South direction/ चुंबकीय उत्तर-दक्षिण दिशा
(b) Polarity of a magnet/ एक चुंबक की ध्रुवीयता
(c) Strength of a magnet/ एक चुंबक की शक्ति
(d) Direction of magnetic field/ चुंबकीय क्षेत्र की दिशा

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Ans.(c)
Sol. A compass needle cannot be used to detect Strength of a magnet.

Q2. Indicate the false statement about the resistance of a wire
एक तार के प्रतिरोध के बारे में गलत कथन को इंगित करें
(a) It depend on material of wire/ यह तार के पदार्थ पर निर्भर करता है
(b) It is unrectly proportional to the length of wire/ यह तार की लंबाई के लिए आनुपातिक है
(c) It is directly proportional to the area of cross-section of wire/यह तार के अनुप्रस्थ काट क्षेत्रफल के लिए समानुपातिक है
(d) Resistance of metallic wire increases with increase in temperature/ तापमान में वृद्धि के साथ धातु के तार का प्रतिरोध बढ़ता है

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Ans.(c)
Sol. The resistance of a current carrying conductor is inversely proportional to the area of cross section of the conductor. The reason is because the resistance occurs due to the collision of electrons/charged particles.So resistance is inversely proportional to area of cross section of the conductor.

Q3.For which of the following substances, the resistance decreases with increase in temperature?
निम्नलिखित पदार्थों में से किसके तापमान में वृद्धि के साथ प्रतिरोध कम हो जाता है?
(a) Pure silicon/ शुद्ध सिलिकॉन
(b) Copper/ तांबा
(c) Nichrome/ निक्रोम
(d) Platinum/ प्लैटिनम

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Ans.(a)
Sol. Pure Silicon at room temperature has perhaps one conduction electron for every 1013 (that’s ten trillion) atoms. Increasing the temperature of intrinsic semiconductors provides more thermal energy for electrons to absorb, and thus will increase the number of conduction electrons. Voila – decreased resistance.

Q4. The ratio of intensity of magnetisation to the magnetisation force is known as
चुंबकत्व की तीव्रता का चुंबकत्व बल से अनुपात को किस रूप में जाना जाता है?
(a) flux density / फ्लक्स घनत्व
(b) susceptibility / संवेदनशीलता
(c) relative permeability / तुलनात्मक भेद्दता
(d) none of the above/इनमें से कोई नहीं

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Ans.(b)
Sol. In electromagnetism, the magnetic susceptibility is one measure of the magnetic properties of a material. The susceptibility indicates whether a material is attracted into or repelled out of a magnetic field.

 

Q5. When a bar magnet is cut into two equal halves, the pole strength of each piece
जब एक बार चुंबक दो बराबर हिस्सों में काटा जाता है, तो प्रत्येक टुकड़े की ध्रुव शक्ति
(a) Becomes double/दुगनी हो जाती है
(b) Becomes half/आधी हो जाती है
(c) Becomes zero/शून्य हो जाती है
(d) Remains the same/समान रहती है

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Ans.(d)
Sol. When a bar magnet is cut into two equal halves, the pole strength of each piece Remains the same.

 

Q6. A closed surface has ‘n’ electric dipole located inside it. The net electric flux emerging out of the surface-
एक बंद सतह में ‘n’ विद्युत द्विध्रुव है। सतह से बाहर निकलने वाला शुद्ध विद्युत प्रवाह कितना होगा?
(a) ne/ε_0
(b) 2e/ε_0
(c) 2ne/ε_0
(d) zero / शून्य

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Ans.(d)
Sol. The net flux will be zero as the electric field lines entering the negative end of the dipole will be exactly cancelled by the electric field lines leaving the positive end of the dipole.


Q7. In electromagnetic induction, the induced charge does not depend on –
विद्युत चुम्बकीय प्रेरण में, प्रेरित चार्ज किस पर निर्भर नहीं करता है –
(a) Change in flux / प्रवाह में बदलाव
(b) time of change of magnetic flux / चुंबकीय प्रवाह के परिवर्तन का समय
(c) Resistance of Coil / वक्र का विरोध
(d) None of the above /इनमें से कोई नहीं

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Ans.(b)
Sol. Induced charge does not depend upon time of change of magnetic flux, as Induced charge Q = n∆T∅R

Q8. Lenz’s law is a consequence of the law of conservation of-
लेनज़ का नियम _________ के संरक्षण के कानून का एक परिणाम है
(a) Charge /चार्ज
(b) Momentum / गति
(c) Energy / ऊर्जा
(d) Mass/द्रव्यमान

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Ans.(c)
Sol. According to Lenz law, the polarity of the induced emf is such that it opposes the change in magnetic flux responsible for its production.


Q9. A magnetic field can be produced by-
एक चुंबकीय क्षेत्र किस के द्वारा उत्पादित किया जा सकता है
(a) A moving charge only /गतिशील चार्ज
(b) A changing electric field only / केवल परिवर्तिनीय विद्युत क्षेत्र
(c) Both (a) and (b)/दोनों (a) और (b)
(d) None of the above /इनमें से कोई नहीं

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Ans.(c)
Sol. Magnetic field is produced both by a moving charge and change in electric field


Q10. The unit of electrical resistance of a conductor is-
एक चालक के विद्युत प्रतिरोध की इकाई है-
(a) fared /फ़रेड
(b) volt /वोल्ट
(c) ampere / एम्पेयर
(d) Ohm /ओहम

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Ans.(d)
Sol. Ohm is the SI unit of electrical resistance. 1 ohm is define as the resistance of a conductor when a potential difference of 1 volt is applied to its ends when a current of 1 ampere flows through it

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