Four wires of same material, the same cross-sectional area and the same length when connected in parallel give a resistance of 0.25 Ω. If the same four wires are connected is series the effective resistance will be
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When one leg of parallel circuit is opened out the total current will
A. Reduce
B. Increase
C. Decrease
D. Become zero
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Two resistors are said to be connected in series when
A. Same current passes in turn through both
B. Both carry the same value of current
C. Total current equals the sum of branch currents
D. Sum of IR drops equals the applied e.m.f.
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Resistance of a tungsten lamp as applied voltage increases
A. Decreases
B. Increases
C. Remains same
D. None of the above
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Three 6 ohm resistors are connected to form a triangle. What is the resistance between any two corners?
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Two copper conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductor will be
A. 160 ohms
B. 80 ohms
C. 20 ohms
D. 10 ohms
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The condition for the validity under Ohm’s law is that
A. resistance must be uniform
B. current should be proportional to the size of the resistance
C. resistance must be wire wound type
D. temperature at positive end should be more than the temperature at negative end
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The condition for the validity under Ohm's law is that
A. Resistance must be uniform
B. Current should be proportional to the size of the resistance
C. Resistance must be wire wound type
D. Temperature at positive end should be more than the temperature at negative end
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Which of the following can have negative temperature coefficient?
A. Compounds of silver
B. Liquid metals
C. Metallic alloys
D. Electrolytes
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Which one of the following does not have negative temperature coefficient?
A. Aluminium
B. Paper
C. Rubber
D. Mica
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The property of a conductor due to which it passes current is called
A. Resistance
B. Reluctance
C. Conductance
D. Inductance
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The substances which have a large number of free electrons and offer a low resistance are called
A. Insulators
B. Inductors
C. Semiconductors
D. Conductors
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The ratio of mass of proton to that of electron is nearly
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Three resistances of 10 ohms, 15 ohms and 30 ohms are connected in parallel.
A. 5 ohms
B. 10 ohms
C. 15 ohms
D. 55 ohms
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Switching of a lamp in house produces noise in the radio. This is because switching operation produces
A. Arcs across separating contacts
B. Mechanical noise of high intensity
C. Both mechanical noise and arc between contacts
D. None of the above
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Which of the following statement is true?
A. A galvanometer with low resistance in parallel is a voltmeter
B. A galvanometer with high resistance in parallel is a voltmeter
C. A galvanometer with low resistance in series is an ammeter
D. A galvanometer with high resistance in series is an ammeter
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The four bulbs of 40 W each are connected in series swift a battery across them, which of the following statement is true?
A. The current through each bulb in same
B. The voltage across each bulb is not same
C. The power dissipation in each bulb is not same
D. None of the above
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A glass rod when rubbed with silk cloth is charged because
A. It takes in proton
B. Its atoms are removed
C. It gives away electrons
D. It gives away positive charge
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Insulating materials have the function of
A. Preventing a short circuit between conducting wires
B. Preventing an open circuit between the voltage source and the load
C. Conducting very large currents
D. Storing very high currents
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When electric current passes through a bucket full of water, lot of bubbling is observed. This suggests that the type of supply is
A. A.C.
B. D.C.
C. Any of above two
D. None of the above
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