# Physics [Electricity & Magnetism] Questions for Railway ALP Stage-II Exam : 30th November 2018

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Q1. Safety fuse wire used in domestic electrical appliances is made of metal of low
घरेलू विद्युत उपकरणों में उपयोग की जाने वाली सुरक्षा फ्यूज तार कम_____ धातु से बना होता है
(a) resistance/ प्रतिरोध
(b) melting point/ गलनांक
(c) specific gravity/ विशिष्ट गुरुत्व
(d) conductance/ प्रवाहकत्त्व
Ans.(b)
Sol. A fuse wire is a single, small gauge made up of a tin coated copper wire material of low melting point, usually contained in a carrier of some sort, providing a weak point in an electrical circuit that will melt on overload and disconnect the electricity load. An alloy of lead and tin coated wire is used as the material of the fuse wire.

Q2. If input frequency of a full wave rectifier be n, then output frequency would be
यदि एक पूर्ण तरंग रेक्टिफायरकी इनपुट आवृत्ति n है, तो उत्पादित आवृत्ति कितनी होगी?
(a) n/2
(b) n
(c) 3n/2
(d) 2n

Ans.(d)
Sol. Frequency is measured by how frequently the period is completed in one second.A Time period (denoted by ‘T’ ) is the time needed for one complete cycle of vibration to pass in a given point. The output signal completes a period twice as fast as the input frequency.

Q3. A transformer works on the principle of
एक ट्रांसफार्मर किसके सिद्धांत पर कार्य करता है
(a) self induction/ स्वत: प्रेरण
(b) mutual induction/ आपसी प्रेरण
(c) generator /जनरेटर
(d) inverter/इन्वर्टर

Ans.(b)
Sol. A transformer consists of two electrically isolated coils and operates on Faraday’s principal of “mutual induction”, in which an EMF is induced in the transformers secondary coil by the magnetic flux generated by the voltages and currents flowing in the primary coil winding.

Q4. In AC circuits, AC meters measure
AC सर्किट में, AC मीटर क्या मापता है?
(a) mean values/ औसत आंकड़े
(b) rms values/ आरएमएस मान
(c) peak values/ पीक मान
(d) mean square values/ माध्य वर्ग मान

Ans.(b)
Sol. In AC circuits, AC meters measure rms values.

Q5. The best material for the core of a transformer is
ट्रांसफार्मर के आन्तरक के लिए सबसे अच्छी सामग्री है
(a) stainless steel/ स्टेनलेस स्टील
(b) mild steel / नरम स्टील
(c) hard steel/ कठोर स्टील
(d) soft iron/सॉफ्ट आयरन

Ans.(d)
Sol. In alternating current (AC) devices they cause energy losses, called core losses, due to hysteresis and eddy currents in applications such as transformers and inductors. “Soft” magnetic materials with low coercivity and hysteresis, such as silicon steel, or soft iron are used.

Q6. Which of the following circuit elements is used to ‘block’ DC in an electronic circuit?
निम्नलिखित में से किस परिपथ तत्व का उपयोग विद्युत परिपथ में DC को ‘ब्लॉक’ करने के लिए किया जाता है?
(a) Resistance/ प्रतिरोध
(b) Capacitance/ कैपेसिटेंस
(c) Inductance/इन्डक्टेंस
(d) None of these/ इनमे से कोई नहीं

Ans.(b)
Sol. Capacitance is used to ‘block’ DC in an electronic circuit.

Q7. In the process of magnetization of a bar
एक बार के चुंबकीकरण की प्रक्रिया में
(a) the entire bulk of the bar gets magnetised/ बार का पूरा आयतन चुंबकीय हो जाता है
(b) only the surface of the bar gets magnetised/ केवल बार की सतह चुंबकीय हो जाती है
(c) only the ends of the bar get magnetised/ केवल बार के सिरे चुंबकीय हो जाते हैं
(d) only some parts of the other layers of the bar get magnetised/ बार की अन्य परतों के केवल कुछ हिस्से चुंबकीय हो जाते हैं
Ans.(a)
Sol. In the process of magnetization of a bar the entire bulk of the bar gets magnetized .
Q8. The metal whose electrical conductivity is more, is
वह धातु जिसका विद्युत चालकता अधिक है, है
(a) copper/ तांबा
(b) aluminium/ एल्युमीनियम
(c) silver/ चांदी
Ans.(c)
Sol. Silver also has the highest thermal conductivity of any element and the highest light reflectance. Although it is the best conductor.

Q9. Water cannot be used to extinguish fire caused by electric current, because
विद्युत प्रवाह के कारण लगी आग बुझाने के लिए पानी का उपयोग नहीं किया जा सकता है, क्योंकि
(a) it may cause electrocution/ यह विद्युत प्रक्षेपण का कारण बन सकता है
(b) it may cause hydrolysis/ यह जल-विश्लेषण का कारण बन सकता है
(c) it may cause electrolysis/ यह विद्युतपघटन का कारण बन सकता है
(d) it may spoil the wiring/ यह तारों को खराब कर सकता है
Ans.(a)
Sol. Water is not used for extinguishing fires caused due to electrical faults because water is good conductor of electricity.If water is poured on an electrical fire,the water could conduct electricity causing the person trying to extinguish the fire to experience an electric shock.

Q10. Superconductors are those elements
सुपरकंडक्टर्स वे तत्व हैं
(a) whose conductivity is intermediate between metals and insulators/ जिनकी चालकता धातुओं और संवाहक के बीच मध्यवर्ती है
(b) whose resistance falls almost to zero at very low temperature/ जिनका प्रतिरोध बहुत कम तापमान पर लगभग शून्य तक गिर जाता है
(c) which turm into insulators at very low temperatures/ जो बहुत कम तापमान पर विसंवाहक में बदल जाता है
(d) which conduct electricity only at super-high temperature/ जो केवल उच्च तापमान पर विद्युत का संचालन करता है
Ans.(b)
Sol. When the conductor is cooled to a temperature below its critical temperature, the electrical resistance drops to zero and that phenomenon is called superconductivity.

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