Two bulbs of 500 W and 200 W rated at 250 V will have resistance ratio as________?
Two bulbs of 500 W and 200 W rated at 250 V will have resistance ratio as________?
A. 4 : 25
B. 25 : 4
C. 2 : 5
D. 5 : 2
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Ohm’s law is not applicable to____________?
Ohm’s law is not applicable to____________?
A. vacuum tubes
B. carbon resistors
C. high voltage circuits
D. circuits with low current densitiesSwitching of a lamp in house produces noise in the radio. This is because switching operation produces________?
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 aboveNichrome wire is an alloy of_____________?
Nichrome wire is an alloy of_____________?
A. lead and zinc
B. chromium and vanadium
C. nickel and chromium
D. copper and silverThe resistance of a conductor varies inversely as___________?
The resistance of a conductor varies inversely as___________?
A. length
B. area of cross-section
C. temperature
D. resistivityIf P is the power of a star connected system then what will be power of an equivalent delta connected system?
If P is the power of a star connected system then what will be power of an equivalent delta connected system?A. P
B. 3P
C. P/3
D. None of the aboveAssume 3 numbers of pure resistive loads each of value R.
When these loads are connected in delta the power in each resistor is V^2/R and the total power is 3×V^2/R.
When these loads are connected in star the voltage applied across each = V/(sqrt of 3). Power in each load becomes = V^2/(3×R) . and the total load is =(3×V^2)/(3×R)=V^2/R. You can see this is 3 times less than the total power when the loads are connected in delta.
One important point is that the loads should withstand higher voltage (line voltage) and higher current when connected in delta than when they are connected in star
so power in delta is 3 time power correct answer is 3Pare the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators______________?
are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators______________?
A. Varistors
B. Thermistor
C. Semi-conductors
D. Variable resistors