3. Electrical fundamentals - Q&A
156 questions found
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The average value of 100 volts peak AC is
- 70.7 volts.
- 141. 4 volts.
- 63.7 volts.
I think this might be incorrect.
i assume the question is looking for the rms value?
the formula for rms is -
peak voltage x 0.707
or
peak voltage / 1.414
both formulas give 70.7 as the answer
am i missing something?
A sine wave has 5 amps RMS value. What is the peak value?
- 7.07 amps.
- 6.37 amps.
- 10 amps.
Please explane tnx
An inductor has 1,000 turns of wire and a cross sectional area of 0.001m2. If the core has a permeability of 0.000,001 and the coil is 0.1m. What is the value of the inductor?
- 100microH.
- 100mH.
- 10mH.
How to solve
An example of a paramagnetic material is
- silver.
- iron.
- glass.
- aluminium.
wrog!!
The temperature of a pure metal can greatly affect the resistance of it. What temperature scale is used?
- Absolute.
- Centigrade.
- Fahrenheit.
answer should be absolute temperature scale , please chnage it
The earth lead of a 24 V equipment is 0.5 ohm resistance and carries 80 A. How much power does it dissipate?
- 1.92 kW.
- 1.152 kW.
- 3.2 kW.
P=VI
so p=24 x 80=1.92 kw
????
A heater which consumes 800 Kilojoules/sec is on for 4hrs 15min. The energy consumed is
- 340 kWh.
- 4 kWh.
- 3400 kWh.
How?
The input is 115V and is applied across the 300 turn portion of the autotransformer shown. What is the output?
- 115V
- 28V
- 460V
how?
One revolution of a three phase generator will produce
- 1 cycle.
- 3 cycles.
- 2 cycles.
3 phase generatir....
that mean 1 rev will produce cycle??
Two inductive coils are placed in close proximity with each other at 90 degrees. The number of flux linkages is
- 0.
- maximum negative.
- maximum positive.
explain..
If the current reaches a maximum through an inductor of 2A in 15 seconds, what is the current after 3 seconds?
- 1.26A.
- 0.63A.
- 1A.
how??
If a capacitor 1uF and an inductor 10mH are connected in parallel what is their approximate resonant frequency?
- 1.6 kHz.
- 62 Hz.
- 3.2 MHz.
how??
A 200 volt motor is taking 10 amperes armature current, the armature resistance is 0.1 ohm. The Back- EMF under these conditions will be
- 201 volts.
- 199 volts.
- 1 volt.
How???
In a Desynn indicator system, the rotor is
- an electromagnet.
- a permanent magnet.
- an AC magnet.
This is the first time i heard.,,
Which is a high-pass filter?
- L type with series L and shunt C.
- L type with series C and shunt L.
- Î type with series C and L.
i dont understand that symbol...
Transformer copper loss on full load is 220 Watts. On half load the loss will be
- 440 Watts.
- 110 Watts.
- 55 Watts.
How???
An electric motor produces a force of 5 N at a distance of 0.2m from the centre of rotation and rotates at a speed of 100 revs/sec. The motors output is
- 100 horsepower.
- 628.4 watts.
- 314.2 watts.
How??
In an inductive resistive circuit, 1 amp flows from a supply of 100V dissipating 50 Watts of power. The phase angle is
- 60degrees.
- 90degrees.
- 45degrees.
Please teach me...
In the circuit shown, if the frequency is increased from zero to resonant frequency, the circuit current would
- increase.
- decrease.
- stay the same.
please explain...
A transformer has 500 turns on the primary and 100 turns on the secondary. The secondary supplies 20V and is connected to a 10 ohm load. The primary current is
- 0.4 amps.
- 2 amps.
- 10 amps.
HOW????
A Transformer has 4500 secondary turns and 750 primary turns. Its turns ratio is
- 1:6.
- 1/6.
- 6:1.
Turn Ratio is Secondary/primary. Hence correct turn ratio is 6:1.
The instantaneous value of the EMF induced in a rotating wire loop is
- directly proportional to the sine of the angle between the loop and the field.
- indirectly proportional to the sine of the angle between the loop and the field.
- directly proportional to the cosine of the angle between the loop and the field.
how do you get cosine?
The RMS value of 200 volts peak to peak is
- 141.4 volts.
- 70.7 volts.
- 127.4 volts.
Pls explain
In a circuit containing three resistors of equal value connected in parallel, one resistor goes open circuit. The current in the other two resistors will
- decrease.
- increase.
- remain the same.
should be 'increase' right ?
The total current flowing in a circuit of 200 lamps in parallel, each of a resistance of 400 ohm and connected across an input of 100 volts is
- 25 amps.
- 50 amps.
- 40 amps.
how?