RWE 1 - ELEX
c
A circuit consists of three resistors connected in parallel. R1= 30 ohms, R2= 15 ohms, and R3=10 ohms. If the current through R2= 4 amperes, what is the total source voltage? a. 20 V b. 120 V c. 60 V d. 220 V
d
A coil of copper wire has a resistance of 100Ω when its temperature is 0C. Determine its resistance at 70C if the temperature coefficient of resistance of copper at 0C is 0.0043/C a. 127.8Ω b. 114.3Ω c. 110.5Ω d. 130.1Ω
d
A current if flowing through a conductor with non-uniform area of cross-section. The current will be? a. different at different cross-sections. b. the same at all cross-sections c. different but current density will be same at all cross-sections d. the same but current density will be different at different cross-sections
a
Assertion(A): Power is the rate at which energy is supplied. Reason(R): Energy=VIt a. Both A and R are true and R is correct explanation of A b. Both A and R are true and R is not the correct explanation of A. c. A is true but R is false. d. A is false but R is true
b
In both carbon resistor colour code, if the third band is of silver, it indicates a. the three zeroes are to be added indicate the resistance value b. multiplier is 0.01 c. multiplier is 0.1 d. tolerance is ±5%
d
Two inductors, having values of 44mH and 88mH, are connected in series with a coefficient of coupling equal to 1.0 (maximum possible mutual inductance). If their fields reinforce, what is the net inductance? a. 7.5 mH b. 190 mH c. 132 mH d. 260 mH
a
Two passive elements are connected in series and a dc voltage is applied to the circuit. The time variation of the current is shown in the figure. The two elements are a. one resistance and the other inductance b. both resistances c. one inductance and the other capacitance d. one resistance and the other capacitance
d
Two resistance of 2Ω each are connected in series. A shunt having zero resistance is connected across the combination. The overall resistance will be a. 4Ω b. 0.5Ω c. 1Ω d. zero
b
Two resistors of 4 ohms and 6 ohms are connected in parallel. If the total current is 30 amperes, find he current through each. a. 17 A and 13 A b. 18 A and 12 A c. 20 A and 30 A d. 16 A and 14 A
a
Voltage drop means: a. voltage developed across the terminals of a component b. any point in a radio circuit which has a zero voltage c. difference in voltage at output terminals of a transformer d. the voltage which is dissipated before useful work is accomplished
d
Wattage rating is maximum power that the resistor can dissipate assuming which of the following factors? a. A specific life b. A standard ambient temperature c. A stated long term drift from its no-load value d. All of the above
a
What capacitance must be connected in series with 30 uF capacitor for the equivalent capacitance be 12uF? a. 20 uF b. 15 uF c. 10 uF d. 25 uF
b
What capacitor terminology includes power factor, loss factor, and dielectric loss? a. quality factor b. tangent of loss angle c. cosine of loss angle d. dissipation factor
c
What ceramic capacitor class includes ceramic dielectrics suitable for fixed capacitors used for bypass, coupling and decoupling applications? a. Class I b. Class III c. Class II d. Class IV
a
What class of ceramic capacitors are stable temperature-compensating capacitors that have essentially linear characteristics with properties independent of frequency over normal range? a. Class I b. Class III c. Class II d. Class IV
b
What do you call the maximum temperature measured on the resistor due to both internal heating and the ambient operating temperature? a. equivalent temperature b. hot-spot temperature c. critical temperature d. curie temperature
a
What do you call this effect: "reduction of the effective resistance of a resistor when operated at VHF or higher frequencies due to dielectric losses"? a. Boella effect b. Johnson's effect c. VHF effect d. Transit time effect
a
What is a small capacitance formed by twisting together two insulated wires? a. gimmick capacitance b. stray capacitance c. diffusion capacitance d. junction capacitance
a
What is the needed ampacity of a superconductor to be commercially available? a. 10,000 A/cm^2 b. 20,000 A/cm^2 c. 30,000 A/cm^2 d. 40,000 A/cm^2
b
What is the percent conductivity of pure annealed copper wire? a. 97.8% b. 102.1% c. 100.0% d. 99.5%
a
What is the percent conductivity of pure annealed silver? a. 108.8% b. 100.0% c. 102.1% d. 99.99%
a
What theorem states that "any branch voltage can be replaced by a branch current, and any branch current can be replaced by a branch voltage, as long as the voltage drop and current through the branch remain the same"? a. Substitution Theorem b. Reciprocity Theorem c. Superposition Theorem d. Norton's Theorem
a
Which one of the following is NOT a common capacitor working voltage? a. 15 V b. 100 V c. 10 V d. 1000 V
c
Which resistor type is more voltage-sensitive than others? a. wirewound resistor b. thin film c. carbon composition d. precision resistor
b
Who invented the Leyden jar, the first capacitor? a. charles coulumb b. peter van musschenbroek c. e.g. von kleist d. william watson
a
Who once stated: "I sell here what all the world desires to have; power." a. James Watt b. James Prescott Joule c. Joseph Priestly d. Alessandro Volta
a
A parallel plate capacitor has nineteen interleaved plates each 75mm by 75 mm separated by mica sheets 0.2 mm thick. Assuming the relative permittivity of the mica is 5, calculate the capacitance of the capacitor. a. 22.4nF b. 26.1nF c. 34.2nF d. 21.8nF
b
A piece of copper wire 0.091 cm in diameter and 3.66 m long has a resistance of 0.1 ohm. Find the specific resistance of copper. a. 17.9 uΩ-cm b. 1.79 uΩ-cm c. 1.79 uΩ-m d. 17.9 uΩ-cm
b
Find the Vth of the circuit shown a. 100V b. 0V c. 10V d. 5V
a
For a given voltage four heating coils will given maximum heat when connected a. in parallel b. in series c. with two parallel pairs in series d. with one pair in parallel and the other two in series
a
In a resistor the current is i and the voltage is v. The rate of dissipation of heat at any time t is a. vi b. vt c. vit d. vit^2
b
In any closed loop in a network, the algebraic sum of the voltage drops (i.e. products of the current and resistance) taken around the loop is equal to the resultant e.m.f. acting in that loop. This is known as: a. Current Law b. Voltage Law c. Power Law d. Inverse Law
c
In any network made up of linear resistances and containing more than one source of emf, the resultant current flowing in any branch is the algebraic sum of the currents that would flow in that branch if each source was considered separately. What is this theorem? a. Thevenin's theorem b. Norton's theorem c. Superposition theorem d. Millman's theorem
c
Maximum power transfer theorem finds application in a. power circuits b. distribution circuits c. communication circuits d. both power and communication circuits
d
Maximum working voltage is the maximum voltage that ma be applied across the resistor and is determined by which of the following devices? a. the materials used b. the allowable resistance deviation from the low-voltage value c. the physical configuration of the resistor d. all of the choices
c
One commercial unit of energy is equal to a. 1 watt-sec b. 1 kilowatt-sec c. 1 kilowatt-hour d. One watt-hour
d
The equivalent inductance measured between the terminals 1 and 2 for the circuit shown in the figure is a. L1+L2+M b. L1+L2-M c. L1+L2+2M d. L1+L2-2M
a
The equivalent inductance seen at terminals A-B is a. 14 H b. 10 H c. 20 H d. 4 H
d
The equivalent resistance between terminals x and y figure is a. 150Ω b. 55Ω c. 45Ω d. 35Ω
c
Why do we tin component leads? a. it helps to oxidize the wires b. prevents rusting of the circuit board c. decreases heating time and aids in connections d. provides ample wetting for good connection
c
Two coils connected in series have self inductance of 40mH and 10mH respectively. The total inductance of the circuit is found to be 60mH. Determine the mutual inductance between the two coils and the coefficient of coupling. a. 5H, 0.23 b. 5uH, 0.21 c. 5mH, 0.25 d. 5nH, 0.24
b
Two coils have inductances of 250mH and 400mH respectively. Determine the magnetic coupling coefficient of the pair of coils if their magnetic inductance is 80mH. a. 0.115 b. 0.253 c. 0.124 d. 0.162
c
What is the maximum ambient temperature for an EIA precision resistor? a. 100C b. 150C c. 125C d. 17C
d
What is the percent conductivity of 99.9% pure gold? a. 99.9 % b. 100.01% c. 108.8% d. 72.6%
d
What parameter refers to the magnitude of change in resistance due to temperature change assuming linear charge? a. Linear coefficient b. Resistance-temperature characteristic c. Linear temperature parameter d. Temperature coefficient
b
What resistance type exhibit little change in effective dc resistance up to frequencies of about 100kHz? a. film resistor b. carbon composition resistor c. wirewound resistor d. intrinsic resistor
a
What resistor type has the best high-frequency performance? a. film type resistor b. carbon composition resistor c. wirewound resistor d. intrinsic resistor
d
What resistor type is unsuited for use above 50 kHz? a. intrinsic resistor b. film resistor c. carbon composition d. wirewound resistor
a
A capacitor is charged with 10mC. If the energy stored is 1.2J find the voltage and the capacitance. a. 240V; 41.67 uF b. 240V; 41.67mF c. 230V; 41.67 uF d. 230V; 41.67mF
d
A capacitor terminology that refers to minute and rapid fluctuations of capacitance? a. burnout b. capacitance proofing c. coronation d. scintillation
c
A certain factory takes 250 A at 220 V. It is supplied through a pair of feeders 73.2 meters long and 1.29 cm^2 in cross section. What voltage must be maintained at the end of the feeders? (us ρ = 1.79uΩ-cm) a. 220 v b. 230 v c. 225 v d. 235 v
d
A piece of silver wire has a resistance of 1 ohm, What will be the resistance of a manganin wire 1/3 the length and 1/3 diameter if the specific resistance of manganin wire is 30 times that of silver? a. 3Ω b. 60Ω c. 30Ω d. 90Ω
a
A single voltage divider provides both negative and positive voltages from a single source voltage through the use of a a. ground between two fo the dividing resistors b. ground to the positive terminal of the source c. ground to the negative terminal of the source d. ground to the input of all loads requiring a negative voltage
a
A waxed paper capacitor has two parallel plates, each of effective area 800 cm^2. If the capacitance of the capacitor is 4425pF determine the effective thickness of the paper if its relative permittivity is 2.5 a. 0.4 mm b. 0.03 mm c. 0.3 mm d. 0.1 mm
b
A wire has a diameter d and resistance R. If the diameter is made 3d, the lengths and material remaining the same, the new value of resistance will be a. R/3 b. R/9 c. 3R d. 9R
b
A wire has a resistance of 5.7Ω. What will be the resistance of another wire of the same material three times as long and one half the cross sectional area? a. 32.4Ω b. 34.2Ω c. 43.2Ω d. 44.2Ω
a
A wire of conductor 0.2 ohms resistance is doubled in length, if its resistance is a. 0.4 ohm b. 0.04 ohm c. 0.2 ohm d. 0.8 ohm
d
A wire with smaller cross-sectional area will produce: a. less heat b. more conductance c. less resistance d. more heat
b
As the diameter of a wire is doubled, the resistance becomes a. twice b. one fourth c. one half d. four times
c
Assertion (A): Millman's theorem helps in replacing a number of current sources in parallel by a single current source. Reason (R): Maximum power transfer theorem is applicable only for dc, circuits. a. Both A and R are true and R is correct explanation of A b. Both A and R are true and R is not the correct explanation of A. c. A is true but R is false. d. A is false but R is true
d
Assertion (A): Superposition theorem can be used to find the output of a full wave rectifier excited by sinusoidal signal sources of different frequencies connected in series. Reason(R): Superposition theorem is valid for all linear systems. a. Both A and R are true and R is correct explanation of A b. Both A and R are true and R is not the correct explanation of A. c. A is true but R is false. d. A is false but R is true
c
Calculate the cross-sectional area, in mm^2, of a piece of copper wire, 40m in length and having resistance of 0.25Ω. Take the resistivity of copper as 0.002x10^-6 mΩ. a. 1.6 mm^2 b. 2.4 mm^2 c. 3.2 mm^2 d. 0.8 mm^2
a
For nonlinear resistance a. v-i plot is not a straight line b. resistance increases as the current increases c. resistance decreases at the current increases d. current decreases as voltage increases
a
If the capacitor is charged by a square wave current source the voltage across the capacitor is a. triangular wave b. step function c. zero d. square wave
b
If the charge in resistance in nonlinear with respect to temperature change then the parameter is called a. temperature coefficient b. resistance-temperature characteristic c. linear temperature parameter d. linear coefficient
d
In the circuit shown in the figure the power dissipated in 30Ω resistor will be maximum if the value of R is a. 30Ω b. 9Ω c. 10Ω d. zero
a
In the figure circuit, V1= 40 V. When R is 10Ω. When R is zero, the value of V2 will be a. 40 V b. 20 V c. 30 V d. 10 V
b
In the figure, the charge on 0.8 uF capacitor is a. 100 uC b. 40 uC c. 50 uC d. 20 uC
a
In the figure, the current through 10V battery is a. 0 b. 0.5 A charging c. 0.5 A discharging d. none of the choices
a
In the figure, the short circuit current through terminal AB will be a. 3A b. 3A c. 1.5A d. 1A
c
The Vth at terminals A and B is equal to a. 0V b. -5V c. 5V d. 3V
a
The color coding of a resistors shows 100 K, ±10%. When the resistance was measured with an ohmmeter, it read a. 95 K b. 120 K c. 80 K d. 85 K
d
The correct relation between energy and charge is a. Energy = voltage/charge b. Charge = Energy x voltage c. Energy = voltage (charge)^0.5 d. Energy = voltage x charge
b
The current rating of a cable depends on a. length of cable b. diameter of cable c. both length and diameter of cable d. none of the above
a
The current through 10Ω resistance in a dc circuit having two emf sources is 3A. If this resistance is changes to 20Ω, the new value of the current will be a. less than 3A b. equal or less than 3A c. equal to or less or more than 3A d. 1.5A
c
The maximum number of equations required to analyze the circuit shown in the figure is (8 branch and 4 nodes) a. 3 b. 6 c. 4 d. 7
b
The power dissipated in 4Ω resistance in figure is a. 64 W b. 16 W c. 32 W d. 8 W
a
The purpose of heating electric appliances is a. to provide safety against shock b. to ensure that appliance works satisfactorily c. to ensure that appliance gets full voltage d. all of the above
c
The resistance of 575 meter of a certain wire is 21.85Ω. How much must be cut-off to reduce the resistance to 14.25Ω? a. 375m b. 300m c. 200m d. 275m
a
The resistance of a coil of wire increases from 40 ohms to 10C to 48.25 ohms at 60C. Find the temperature coefficient at 0C of the conductor material. A. 0.0043 b. 0.00043 c. 0.043 d. 0.43
b
The total inductance of two coils is 60mH in series aiding connection and 40 mH in series opposing connection. The mutual inductance between coils is a. 20mH b. 5mH c. 10mH d. 2.5mH
b
The value of the inductance of coil in which a current increases linearly from zero to 0.1A in 0.2 second producing a voltage of 5 volts is a. 2.5 b. 10 c. 5 d. 20
c
Thevenin's theorem is used to find current in a branch of a network. It is now desired to find current in another branch of network a. the same Thevenin's circuit can be used b. the same Thevenin's circuit with some modification can be used c. it is necessary to find the new Thevenin's circuit d. either (B) or (C)
a
Three equal resistors are connected in parallel and each resistor has an ohmic value of 300 ohms. What is the equivalent resistance of the circuit? a. 100 Ω b. 600 Ω c. 150 Ω d. 900 Ω
a
Three resistances of 15Ω, 10Ω, and 3Ω are connected in parallel. The overall resistance is a. less than 3Ω b. between 15Ω and 10Ω c. between 10Ω and 3Ω d. more than 3Ω
c
Three resistors with ohmic values of 120 ohms, 60 ohms, and 40 ohms are connected in parallel. What is the equivalent resistance of the circuit? a. 10Ω b. 30Ω c. 20Ω d. 40Ω
b
Three resistors with ohmic values of 120 ohms, 60 ohms, and 40 ohms, are connected in parallel. What is the equivalent resistance of the circuit? a. 10Ω b. 20Ω c. 30Ω d. 40Ω
a
To determine the polarity of voltage drop across a resistor, it is sufficient to know a. direction of current through the resistor b. direction and magnitude of current through the resistor c. direction and magnitude of current and value of resistance d. magnitude of current through the resistance
c
To find current in a resistance connected in a network, Thevenin's theorem is used Vth=20V and Rth=5Ω. The current through the resistance a. is 4A b. is 4A or less c. is less than 4A d. may be 4 A or less or more than 4A
b
To find the current in a 20Ω resistance connected in a circuit, Norton's theorem is used. In=7.5 A. The current through 20Ω resistance a. is 7.5 A b. is less than 75 A c. may be 7.5 A or less d. may be 7.5 A or more or less
b
When maximum power transferred from a source to a load, what is the efficiency of power transfer? a. 5% b. 50% c. 25% d. 95%
d
Which of the following capacitor terminology refers to the ratio by which the capacitance is increased when another dielectric replaces a vacuum between two electrodes? a. relative capacitivity b. relative permittivity c. dielectric constant d. all of the choices
b
Which of the following is not a typical percent tolerance of the EIA precision resistor? a. ±0.05% b. ±1.5% c. ±1.0% d. ±0.1%
a
Which of the following is the typical range of values for ceramic disk type capacitors? a. 1pF to 0.22 uF b. 10 pF to 2 uF c. 10 uF to 100 uF d. 100 pF to 100 uF
d
Which of the following theorems can be conveniently used to find power consumed in 10Ω resistor in the figure? a. Thevenin theorem b. Maximum power transfer theorem c. Millman's theorem d. Superposition theorem
c
Which of the following two quantities should be multiplied together to find power? a. Inductance and capacitance b. Voltage and inductance c. Voltage and current d. Resistance and capacitance
d
Which of the follwing is the poorest conductor of electricity? a. copper b. manganin c. aluminum d. nichrome