問題一覧
1
The presence of electric current is only made known by the effect it produces. Three important effects are
heating, magnetic & electric shock
2
Out of the following select the best conductor of electricity
Graphite
3
For a carbon composition resistor. A resistance of 0.47 ohm will be represented by
yellow, violet & silver
4
Electric pressure in an electric circuit is alsi called
voltage
5
What is the other term for american Wire gauge?
Brown & Sharpe
6
What is the size in square millimeter is the cable 250 MCM size?
126.675
7
What is the equivalent area in sq. inch for a conductor 336,400 circular mil?
0.264
8
A stranded conductor composed of 12 strands each of 0.0808 inch diameter has an resistance of 14.8 ohms. What resistance of conductor of the same length and materials composed of 10 strands each of diameter 0.1016 inch.
11.23 ohms
9
Suppose that you wish to fabricate a uniform out of 1.0 gram of copper. The resistance of wire is to be 0.5 ohm and if all of the copper are to be used, what will be the diameter of wire? Specific resistance is 1.7 × 10^-8 ohm meter and mass density is 8.92 × 10^3 kg/m^3
280
10
A one meter rod of 2 cm diameter is drawn until its resistance is 100 times the initial resistance, its length afterward is?
10 m
11
The resistance of a transformer winding is 0.25 ohm at 25°C. When operating at full load the temperature of the winding is 75°C. The temperature coefficient of resistance for copper is 0.00427 °C. What is the winding resistance at full load?
0.298 ohm
12
A light bulb having a tungsen filament drawns 0.5 Amp at 110 Volts. The cold resistance of the filament is 20 ohms at 20°C with temperature coefficient of residtance for tungsten at this temperature of 0.005 per °C. Determine the operating temperature of the bulb.
2020°C
13
* Two wires of the same material have the same lenght but different diameters. They are connected in series to a battery. Which of the following quantity is the same for the two wires?
current
14
* Two resistor are connected in PARALLEL across a potential difference. The resistance of resistor A is twice that of resistor B. If the current carried by resistor A is I. then what is the current carried by resistor B?
2 I
15
Two resistance R1 and R2 are connected in series across the voltage source where R2 > R1. the largest drop will be across
R2
16
Which of the following statement is TRUE both for series and a parallel DC circuit?
power are additive
17
The voltage applied across the resistor was reduced by 50%. The power consumed is reduced by
75%
18
* The resistance of resistor 1 is twice of resistor 2. The two are connected in SERIES and a potential difference is maintained across the combination. What is the rate of thermal energy generation in resistor 1?
Twice that in resistor 2
19
* A resistor with resistance R1 and resistor with resistance R2 are connected in parallel to an ideal battery with emf V. What is the rate of thermal energy generation in the resistor with resistance R1?
V^2/R1
20
Three resistance are connected in series has a total resistance of 120 ohms. If Rx = 20 ohms. and Ry is twice greater than Rz. Find Ry and Rz
Ry= 75 ohms & Rz= 25 ohms
21
Two 50 ohms resistor are connected in series across 120 volts dc source. Find the value of resistor R in ohms to be connected across one of the two 50 ohm so that the total resistance is 75 ohms
50
22
Four wires of same materials, same criss sectional area and same lenght when connected in parallel gives a resistance of 0.25 ohms. if the same four wire are connected in series the effective resistance will be
4 ohms
23
Over charging of lead acid battery is likely to result in
Sedimentation
24
What will happen if a lead acid battery is kept in discharged condition for long time?
the plates will become sulphated
25
What is the watt hour efficiency of storage battery?
WH output based on WH input in recharge
26
It was experimentally found by james predcott joule that the heat produced in a current carrying conductor is proportionsl to
I^2
27
A seried loop contains the following circuit elements in order an 8 Volt source 2 kohm resistor? Source voltage are additive
4 volts
28
How many eng per second are there in one watt?
10 exp 7
29
A 100 liters of water is heated from 20°C to 40°C. How many kWhr of electricity is needed assuming ni heat loss?
2.3
30
A 2.3 kWh is used to heat 100 liters of water. What is the change in temperature in degrees Fahrenhiet?
36
31
Power in Watts is required to melt 10 lbs ice in 5 minutes. ( latent heat of ice is 80 Calories per gram Calorie is 4.184 Joules) What is the cost operation if power rste is php 6.00/kWh?
2.54
32
Six (6) batteried are connected in parallel supplies a walkman rated 1.5 volts, 1.5 mAmp. Each battery stores 2 watt sec of energy. How long it will take to drain the batteries completely?
1.5 hr
33
Kirchoff's law is not applicable to circuit with
distributed parameters
34
Which of the following statementd is TRUE?
An ideal voltage source can be in parallel with an open circuit.
35
Two batteries sre connected in parallel supply a load taking 60 watts. First battery has 10.5 Volt emf and 0.5 ohm internal resistance while second has 9 volt emf and 0.4 ohm internal resistance. Find the resistance of the load.
1.067 ohms
36
Find the current in the 3 ohm resistor of the circuit of fig. 4 by Thevenin's theorem.
5.143 Amp
37
Find the output voltage in the network
4 Volts
38
Calculate the thevenin voltage & resistance at terminal ab from circuit shown
22.50 Volts, 10 ohms
39
Determine the total current supplied by a battery to the resistive network shown
0.3 Amp
40
A voltage source delivers 4 Amp when load connected to it 5 ohms and 2 Amp when the load becomes 20 ohms. What maximum power which the source can suppy?
90 watts
41
The unit of relative permeability is _______
it is dimensionless
42
The unit of magnetic flux is the same as that of_________
pole strength
43
What is the hesting process makes use of the current induced by the electromagnetic action in the heated, used for hardening of steel
Induction heating
44
* A flux of 13.6 milliweber penetrates a coil of wire 240 mm in diameter. Find the magnitude of the magnetic flux density in telsa if the plane of the coil is perpendicular to the field?
0.3
45
Determine the force in pounds upon each side of a coil of 40 turns carrying a current of 15 Amp of the axial length if the coil is 10 inch and flux density is 20,000 lines per sq. inch. The conductors are at night angle to the flux
10.6 lbs
46
A long straight conductor is carrying 100Amp current. Determine the flux density at a point 8 cm from the conductor
0.25×10^-3
47
An air core soleniod 0.5 m long has 2000 turns. The magnetic induction near the center of the soleniod is 0.08 tesla. What is the current in the soleniod?
16 Amp
48
A soleniod has 250 turns. What is the mmf when the current is 0.12 Amp?
37.7 Gilberts
49
Two long parallel conductors carry 100 Amp. If the conductors are seperated by 20 mm, the force per meter length of each conductor will be ______
0.1 N
50
An iron ring electromagnet having a relative permesbility of 1250 when it is excited by a coil having 500 turns at 0.8 Amp. The mean length of iron parts is 48 cm, the cross section of core is 10 cm^2, and the air cap is 0.5 cm. what is its totsl reluctance?
4286×10^3 AT/Wb
51
A magnetic circuit consists of silicon steel 3000 permeability of 10 cm length and cross section of 1.5 sq.cm and an air gap of the same cross section and of 2 cm, the cross section of core is 500 turns. What is the field intendity at the sir gap?
1,567
52
The relative permeability of a certain silicon steel is 4,500. A certsin magnetic loop consists of a silicon steel of 10 cm square 20 cm long and an air gap of 1/4 cm. What is the reluctance of magnetic circuit?
2.54×10^-2
53
A south pole of 35 unit pole is placed under a south pole 20 unit pole is 1 inch apart. What is the force between them?
108.5 dynes repulsion
54
A coil of 100 turns is cut by a magnetic field that increases at the rate of 40 mWb/sec. What is the induced voltage?
40 V
55
* The current in a coil decreases from 30 Amp to 10 Amp in 0.2 sec. If the self inductance of coil is 4 henry. What is the induced emf in volts?
400
56
How much energy is stored in the magnetic field of a 50 milllihenry coil carrying a steady current of 3 Amp?
0.225 Joule
57
The flux density emanating from a pole of a generator is 20,000 gauss. A conductor one meterlong cuts the flux perpendicularly at a speed of 40 m per second. What voltage is developed?
80 Volts
58
A coil consists of 1000 turns of wire uniformly wound onna non-magnetic ring of mean diameter 40 cm and cross sectional area of 20 cm^2. Calculate the inductance of the coil.
2mH
59
Two coils having inductance L1 = 0.5 H, L2 0.3 H. at one instant l1 = 12 A and l2 = 5 A. Find the total energy stored when the coefficient of coupling is M= - 0.45 H
12.75 J
60
A soleniod has 800 turns a current of 5 Amp in the winding produces a flux of 0.025 Weber
8 H
61
Three induction L1 = 20 mH, L2 = 20 mH and L3 = 40 mH connected in parallel. Determine the equvalent inductance
8 mH
62
A non magnetic ring having a mean diameter of 30 cm the cross sectional area is 4 sq.cm and uniformly wound with two conductors A and B over one another. A has 90 turns 240 turns. Calculate the first principle of mutual inductance between the core.
10.62
63
Two coils A and B are on the same magnetic circuit. The inductance of coil A alone is measure and found to be 600 mH the inductance of coil B id like wise found to be 320 mH. The inductsnce of the two coils in series aiding is then measured and found to be 1314 mH. Determine the coupling coeffienct.
0.45
64
When two inductors are connected in series aiding thier total inductance in 40 mH, when connected series opposing the indictance is 17.5 mH. What is the value of mutual inductance?
5.625
65
Which of the following materials has the highest value of dielectric constant?
ceramics
66
The force between two electrons in vacuum is 1 × 10^-15 Newton. How far apart are the electrons?
4.80×10^-7 m
67
Two solid sphred have charges of 1 coulomb and -8 Coulomb respectively. The permittivity. Eo= 8.85 x 10^-12 Coul^2/N-m^2 and the distance between the sphere centers r is 0.3 meters. Determine the force on the sphere
-8 x 10^11 N
68
Three equal posistive charges of 10 stat Coulomb each are located at the vertices of an equilateral traingle of 2 cm leg. What is the magnitude of the force acting on each charges?
43.3 dynes
69
In parallel plate capscitor of capacitance Co the electric field is E. If the dielectric slab with dielectric constant equal to 7 is introduced to fill the capacitor completely, the electric field will become?
E/7
70
* Approximately how far away must an isolated positive point charge of 1x10^-8 Coul be in order for it to produce an electric potential of 100 volts. The charges in free space with E = 8.85 x 10 ^-12 Coul/N-m^2
0.90 m
71
A charge of 0.75 Coulombs passes through a wire every 15 seconds. What is the current in the wire?
75 mA
72
The capacitance of a capacitor formed by two parallel metal plate each of 200 sq.cm in area seperated by a dielectric 1 mm thick is 4.5 x 10^-4 micro farad. What is the dielectric constat of the material?
2.54
73
A certain capacitor is charged at 48 Volts after which its energy is 5.76 x 10 to negative 2 Joule. What is the capacitance of the capacitor?
50 micro-farad
74
Find the connection of capacitor C1 = 1 uF, C2 = 3 uF and C3 = 4 uF needed to have a total of 2 uF.
C1 & C2 in parallel series with C3
75
Two condensers of 3 uF and 5 uF respectively are connected in parallel. The combination is charge with 0.0056 Coul. The charge in the 3 uF condenser is?
0.0021 Coul
76
A capacitor is charged in 100 Volts. when it is in paralleled to 1 micro farad capscitor and the voltage is 70 volts. What is the value of unknown capacitor in microfarad?
2.33
77
A 12 micro-farad capacitor charged at 500 volts and a 6 micro-farad capscitor charged at 250 volts are connected in parallel. What is the potential difference in the combination?
417 Volts
78
A galvanometer has a resistance of 300 ohms. What is the ohmic resistance to make it read on is to ten?
33.33
79
A 100,000- ohm voltmeter is used in measuring the insulation resistance of a motor. When connected in series with the insulation across a 250 volt line. the instrument reads 1 volt. What is the insulation resistance of the motor?
24.9 Mohm
80
In the test of a 10 Amp Watt hour meter having a constant of 0.4. the disk makes 40 revolution in 53.6 sec. The average Volts and Amperes during this period are 116 volts and 9.4 Amp. What is the error of the meter at this period?
1.4% slower
DC CIRCUITS POWERLINE
DC CIRCUITS POWERLINE
premopremo remo · 75問 · 2年前DC CIRCUITS POWERLINE
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premopremo remo · 99問 · 1年前EE REFRESHER 4
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premopremo remo · 32問 · 1年前MATH MULTIVECTOR
MATH MULTIVECTOR
32問 • 1年前問題一覧
1
The presence of electric current is only made known by the effect it produces. Three important effects are
heating, magnetic & electric shock
2
Out of the following select the best conductor of electricity
Graphite
3
For a carbon composition resistor. A resistance of 0.47 ohm will be represented by
yellow, violet & silver
4
Electric pressure in an electric circuit is alsi called
voltage
5
What is the other term for american Wire gauge?
Brown & Sharpe
6
What is the size in square millimeter is the cable 250 MCM size?
126.675
7
What is the equivalent area in sq. inch for a conductor 336,400 circular mil?
0.264
8
A stranded conductor composed of 12 strands each of 0.0808 inch diameter has an resistance of 14.8 ohms. What resistance of conductor of the same length and materials composed of 10 strands each of diameter 0.1016 inch.
11.23 ohms
9
Suppose that you wish to fabricate a uniform out of 1.0 gram of copper. The resistance of wire is to be 0.5 ohm and if all of the copper are to be used, what will be the diameter of wire? Specific resistance is 1.7 × 10^-8 ohm meter and mass density is 8.92 × 10^3 kg/m^3
280
10
A one meter rod of 2 cm diameter is drawn until its resistance is 100 times the initial resistance, its length afterward is?
10 m
11
The resistance of a transformer winding is 0.25 ohm at 25°C. When operating at full load the temperature of the winding is 75°C. The temperature coefficient of resistance for copper is 0.00427 °C. What is the winding resistance at full load?
0.298 ohm
12
A light bulb having a tungsen filament drawns 0.5 Amp at 110 Volts. The cold resistance of the filament is 20 ohms at 20°C with temperature coefficient of residtance for tungsten at this temperature of 0.005 per °C. Determine the operating temperature of the bulb.
2020°C
13
* Two wires of the same material have the same lenght but different diameters. They are connected in series to a battery. Which of the following quantity is the same for the two wires?
current
14
* Two resistor are connected in PARALLEL across a potential difference. The resistance of resistor A is twice that of resistor B. If the current carried by resistor A is I. then what is the current carried by resistor B?
2 I
15
Two resistance R1 and R2 are connected in series across the voltage source where R2 > R1. the largest drop will be across
R2
16
Which of the following statement is TRUE both for series and a parallel DC circuit?
power are additive
17
The voltage applied across the resistor was reduced by 50%. The power consumed is reduced by
75%
18
* The resistance of resistor 1 is twice of resistor 2. The two are connected in SERIES and a potential difference is maintained across the combination. What is the rate of thermal energy generation in resistor 1?
Twice that in resistor 2
19
* A resistor with resistance R1 and resistor with resistance R2 are connected in parallel to an ideal battery with emf V. What is the rate of thermal energy generation in the resistor with resistance R1?
V^2/R1
20
Three resistance are connected in series has a total resistance of 120 ohms. If Rx = 20 ohms. and Ry is twice greater than Rz. Find Ry and Rz
Ry= 75 ohms & Rz= 25 ohms
21
Two 50 ohms resistor are connected in series across 120 volts dc source. Find the value of resistor R in ohms to be connected across one of the two 50 ohm so that the total resistance is 75 ohms
50
22
Four wires of same materials, same criss sectional area and same lenght when connected in parallel gives a resistance of 0.25 ohms. if the same four wire are connected in series the effective resistance will be
4 ohms
23
Over charging of lead acid battery is likely to result in
Sedimentation
24
What will happen if a lead acid battery is kept in discharged condition for long time?
the plates will become sulphated
25
What is the watt hour efficiency of storage battery?
WH output based on WH input in recharge
26
It was experimentally found by james predcott joule that the heat produced in a current carrying conductor is proportionsl to
I^2
27
A seried loop contains the following circuit elements in order an 8 Volt source 2 kohm resistor? Source voltage are additive
4 volts
28
How many eng per second are there in one watt?
10 exp 7
29
A 100 liters of water is heated from 20°C to 40°C. How many kWhr of electricity is needed assuming ni heat loss?
2.3
30
A 2.3 kWh is used to heat 100 liters of water. What is the change in temperature in degrees Fahrenhiet?
36
31
Power in Watts is required to melt 10 lbs ice in 5 minutes. ( latent heat of ice is 80 Calories per gram Calorie is 4.184 Joules) What is the cost operation if power rste is php 6.00/kWh?
2.54
32
Six (6) batteried are connected in parallel supplies a walkman rated 1.5 volts, 1.5 mAmp. Each battery stores 2 watt sec of energy. How long it will take to drain the batteries completely?
1.5 hr
33
Kirchoff's law is not applicable to circuit with
distributed parameters
34
Which of the following statementd is TRUE?
An ideal voltage source can be in parallel with an open circuit.
35
Two batteries sre connected in parallel supply a load taking 60 watts. First battery has 10.5 Volt emf and 0.5 ohm internal resistance while second has 9 volt emf and 0.4 ohm internal resistance. Find the resistance of the load.
1.067 ohms
36
Find the current in the 3 ohm resistor of the circuit of fig. 4 by Thevenin's theorem.
5.143 Amp
37
Find the output voltage in the network
4 Volts
38
Calculate the thevenin voltage & resistance at terminal ab from circuit shown
22.50 Volts, 10 ohms
39
Determine the total current supplied by a battery to the resistive network shown
0.3 Amp
40
A voltage source delivers 4 Amp when load connected to it 5 ohms and 2 Amp when the load becomes 20 ohms. What maximum power which the source can suppy?
90 watts
41
The unit of relative permeability is _______
it is dimensionless
42
The unit of magnetic flux is the same as that of_________
pole strength
43
What is the hesting process makes use of the current induced by the electromagnetic action in the heated, used for hardening of steel
Induction heating
44
* A flux of 13.6 milliweber penetrates a coil of wire 240 mm in diameter. Find the magnitude of the magnetic flux density in telsa if the plane of the coil is perpendicular to the field?
0.3
45
Determine the force in pounds upon each side of a coil of 40 turns carrying a current of 15 Amp of the axial length if the coil is 10 inch and flux density is 20,000 lines per sq. inch. The conductors are at night angle to the flux
10.6 lbs
46
A long straight conductor is carrying 100Amp current. Determine the flux density at a point 8 cm from the conductor
0.25×10^-3
47
An air core soleniod 0.5 m long has 2000 turns. The magnetic induction near the center of the soleniod is 0.08 tesla. What is the current in the soleniod?
16 Amp
48
A soleniod has 250 turns. What is the mmf when the current is 0.12 Amp?
37.7 Gilberts
49
Two long parallel conductors carry 100 Amp. If the conductors are seperated by 20 mm, the force per meter length of each conductor will be ______
0.1 N
50
An iron ring electromagnet having a relative permesbility of 1250 when it is excited by a coil having 500 turns at 0.8 Amp. The mean length of iron parts is 48 cm, the cross section of core is 10 cm^2, and the air cap is 0.5 cm. what is its totsl reluctance?
4286×10^3 AT/Wb
51
A magnetic circuit consists of silicon steel 3000 permeability of 10 cm length and cross section of 1.5 sq.cm and an air gap of the same cross section and of 2 cm, the cross section of core is 500 turns. What is the field intendity at the sir gap?
1,567
52
The relative permeability of a certain silicon steel is 4,500. A certsin magnetic loop consists of a silicon steel of 10 cm square 20 cm long and an air gap of 1/4 cm. What is the reluctance of magnetic circuit?
2.54×10^-2
53
A south pole of 35 unit pole is placed under a south pole 20 unit pole is 1 inch apart. What is the force between them?
108.5 dynes repulsion
54
A coil of 100 turns is cut by a magnetic field that increases at the rate of 40 mWb/sec. What is the induced voltage?
40 V
55
* The current in a coil decreases from 30 Amp to 10 Amp in 0.2 sec. If the self inductance of coil is 4 henry. What is the induced emf in volts?
400
56
How much energy is stored in the magnetic field of a 50 milllihenry coil carrying a steady current of 3 Amp?
0.225 Joule
57
The flux density emanating from a pole of a generator is 20,000 gauss. A conductor one meterlong cuts the flux perpendicularly at a speed of 40 m per second. What voltage is developed?
80 Volts
58
A coil consists of 1000 turns of wire uniformly wound onna non-magnetic ring of mean diameter 40 cm and cross sectional area of 20 cm^2. Calculate the inductance of the coil.
2mH
59
Two coils having inductance L1 = 0.5 H, L2 0.3 H. at one instant l1 = 12 A and l2 = 5 A. Find the total energy stored when the coefficient of coupling is M= - 0.45 H
12.75 J
60
A soleniod has 800 turns a current of 5 Amp in the winding produces a flux of 0.025 Weber
8 H
61
Three induction L1 = 20 mH, L2 = 20 mH and L3 = 40 mH connected in parallel. Determine the equvalent inductance
8 mH
62
A non magnetic ring having a mean diameter of 30 cm the cross sectional area is 4 sq.cm and uniformly wound with two conductors A and B over one another. A has 90 turns 240 turns. Calculate the first principle of mutual inductance between the core.
10.62
63
Two coils A and B are on the same magnetic circuit. The inductance of coil A alone is measure and found to be 600 mH the inductance of coil B id like wise found to be 320 mH. The inductsnce of the two coils in series aiding is then measured and found to be 1314 mH. Determine the coupling coeffienct.
0.45
64
When two inductors are connected in series aiding thier total inductance in 40 mH, when connected series opposing the indictance is 17.5 mH. What is the value of mutual inductance?
5.625
65
Which of the following materials has the highest value of dielectric constant?
ceramics
66
The force between two electrons in vacuum is 1 × 10^-15 Newton. How far apart are the electrons?
4.80×10^-7 m
67
Two solid sphred have charges of 1 coulomb and -8 Coulomb respectively. The permittivity. Eo= 8.85 x 10^-12 Coul^2/N-m^2 and the distance between the sphere centers r is 0.3 meters. Determine the force on the sphere
-8 x 10^11 N
68
Three equal posistive charges of 10 stat Coulomb each are located at the vertices of an equilateral traingle of 2 cm leg. What is the magnitude of the force acting on each charges?
43.3 dynes
69
In parallel plate capscitor of capacitance Co the electric field is E. If the dielectric slab with dielectric constant equal to 7 is introduced to fill the capacitor completely, the electric field will become?
E/7
70
* Approximately how far away must an isolated positive point charge of 1x10^-8 Coul be in order for it to produce an electric potential of 100 volts. The charges in free space with E = 8.85 x 10 ^-12 Coul/N-m^2
0.90 m
71
A charge of 0.75 Coulombs passes through a wire every 15 seconds. What is the current in the wire?
75 mA
72
The capacitance of a capacitor formed by two parallel metal plate each of 200 sq.cm in area seperated by a dielectric 1 mm thick is 4.5 x 10^-4 micro farad. What is the dielectric constat of the material?
2.54
73
A certain capacitor is charged at 48 Volts after which its energy is 5.76 x 10 to negative 2 Joule. What is the capacitance of the capacitor?
50 micro-farad
74
Find the connection of capacitor C1 = 1 uF, C2 = 3 uF and C3 = 4 uF needed to have a total of 2 uF.
C1 & C2 in parallel series with C3
75
Two condensers of 3 uF and 5 uF respectively are connected in parallel. The combination is charge with 0.0056 Coul. The charge in the 3 uF condenser is?
0.0021 Coul
76
A capacitor is charged in 100 Volts. when it is in paralleled to 1 micro farad capscitor and the voltage is 70 volts. What is the value of unknown capacitor in microfarad?
2.33
77
A 12 micro-farad capacitor charged at 500 volts and a 6 micro-farad capscitor charged at 250 volts are connected in parallel. What is the potential difference in the combination?
417 Volts
78
A galvanometer has a resistance of 300 ohms. What is the ohmic resistance to make it read on is to ten?
33.33
79
A 100,000- ohm voltmeter is used in measuring the insulation resistance of a motor. When connected in series with the insulation across a 250 volt line. the instrument reads 1 volt. What is the insulation resistance of the motor?
24.9 Mohm
80
In the test of a 10 Amp Watt hour meter having a constant of 0.4. the disk makes 40 revolution in 53.6 sec. The average Volts and Amperes during this period are 116 volts and 9.4 Amp. What is the error of the meter at this period?
1.4% slower