ISBT Reasoning for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams


1) R1 2) R2
3) R3 4) R4
5)None of these
Answer : R3
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if there are b branches and n nodes the number of equations will be
1) n-1 2) b
3) b-n 4) b-n+1
5)None of these
Answer : b-n+1
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The minimum requirements for causing flow of current are
1) a voltage source,a resistor, and a switch. 2) a voltage source and a conductor
3) a power source and a bulb 4) a voltage source,a conductor,an ammeter and a switch
5)None of these
Answer : a voltage source and a conductor
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Due to the existence of  which of the following, the current flowing in an electrical circuit ?
1) mmf 2) emf
3) Resistance 4) Reluctance
5)None of these
Answer : emf
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 In a linear system, an input of 5 sin wt produces an output of 10 cos wt. The output corresponding to input 10 cos wt will be equal to - 
1) + 5 sin wt 2) - 5 sin wt
3) + 20 sin wt 4) – 20 sin wt.
5)None of these
Answer : – 20 sin wt.
Explanation :

Sin wtCos wt Differentiating

       Cos wt2 Sin wt

An input of 10 Cos wt will cause a

Response of – 20 Sin wt.
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 For an SCR, di/dt protection is achieved through the use of  which of the following series ? 
1) R in series with SCR 2) L in series with SCR
3) RL in series with SCR 4) RLC in series with SCR
5)None of these
Answer : L in series with SCR
Explanation : For an SCR, di/dt protection is achieved through the used of L in series with SCR. A snubber circuit connected across an SCR is to suppress dv / dt.
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The electric field lines and equipotential lines - 
1) Are parallel to each other 2) Are one and the same
3) Cut each other orthogonally 4) Can be inclined to each other at any angle
5)None of these
Answer : Cut each other orthogonally
Explanation : Since no electric can exist along any surface, all points of which are at the same potential, electric field lines and equipotential lines are orthogonal to each other.
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The resistance of a strip of copper of rectangular cross-section is 2 ohm. A metal of resistivity twice that of copper is coated on its upper surface to a thickness equal to that of copper strip.  The resistance of composite strip will be - ( DRDO Exam. 2013)
1) 6 ohms 2) 4/3 ohms
3) 3/2 ohms 4) 3/4 ohms
5)None of these
Answer : 4/3 ohms
Explanation : Copper and coated metal strips have resistance of 2 ohms and 4 ohms respectively. 
These two strips are in parallel. Hence the resistance of the composite strip will be (2x4) / (2+4) = 4/3 ohms.
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What is the current rating of MCB, when it is used for 165 litre refrigirators ?
1) 2 amps 2) 4 amps
3) 1.5 amps 4) 7.5 amps
5)None of these
Answer : 2 amps
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A  network consists of linear resistors and ideal voltage source. If the value of the resistors are doubled, then voltage across each resistor is - 
1) halved 2) doubled
3) increases four lines 4) not changed
5)None of these
Answer : not changed
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