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Quiz von Owen Ryan Ang, aktualisiert more than 1 year ago
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Erstellt von Owen Ryan Ang
vor mehr als 4 Jahre
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Frage 1
Frage
What are the minimum requirements to cause the flow of current?
Antworten
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A voltage source, an ammeter, a conductor and an insulator
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A voltage source, a switch and a resistor
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A voltage source and a conductor
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A voltage source, a conductor and an insulator
Frage 2
Frage
Out of the following, select the best conductor of electricity.
Antworten
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Graphite
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China Clay
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Porcelain
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None of these
Frage 3
Frage
Which of the following statements is correct?
Antworten
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The resistance does not play an important role in electrical engineering.
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The resistance of a wire does not depend upon its material.
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The resistance of most of the materials is independent of the temperature.
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The resistance of conductor is the hindrance by which the conductor opposes the flow of the current.
Frage 4
Frage
Resistance of a conductor increases when
Antworten
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its length increases
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its area increases
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both length and area increases
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specific resistance is kept constant
Frage 5
Frage
The specific resistance ρ depends upon
Antworten
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The area of cross-section and the length of the conductor
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The material of the conductor, its area of cress-section and length
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The nature of the material of the conductor only
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The area of cross-section of the conductor
Frage 6
Frage
The specific resistance ρ is defined as
Antworten
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resistance of a conductor which has a length of 1 m and cross-section of 1 m2 at 20C
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resistance of any conductor at 25C
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resistance of any conductor at 20C
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resistance of a conductor which has a length of 1 m and cross-section of 1 cm2 at 20C
Frage 7
Frage
The resistance of a conductor, when its temperature is increased
Antworten
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remains constant
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increases
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varies
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decreases
Frage 8
Frage
It was experimentally found by James Prescott Joule that the heat produced in a current carrying conductor is proportional to
Antworten
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the square of the current
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square of resistance
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the current
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inversely proportional to time
Frage 9
Frage
The value of Joule's mechanical equivalent of heat, J, is equal to
Antworten
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4.2 calories per Joule
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2.4 Joules per calorie
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4.2 Joules per calorie
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4.2 Joules
Frage 10
Frage
Temperature coefficient of a conductor is defined as the
Antworten
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increase in resistance per ohm per degree centigrade
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increase in resistance per degree centigrade
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increase in resistance per degree absolute
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decrease in resistance per ohm per degree centigrade
Frage 11
Frage
When current flows in a conductor, heat is produced because
Antworten
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heat α I²
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of electronic collision
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of interatomic collision
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of Joule's law
Frage 12
Frage
Heating effect of current has undesirable side effect in
Antworten
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electric oven
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electric iron
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immersion heater
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vacuum cleaner
Frage 13
Frage
The resistance of carbon (filament in carbon-filament lamps) when its temperature is decreased
Antworten
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increases
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decreases
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remains the same
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increases enormously
Frage 14
Frage
The curve representing Ohm's law is
Antworten
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a parabola
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linear
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sine function
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a hyperbola
Frage 15
Frage
The condition in Ohm's law is that
Antworten
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ratio V/I should be constant
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current should be proportional to voltage
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the temperature should remain constant
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the temperature should vary
Frage 16
Frage
Ohm's law does not apply to
Antworten
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conductors
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conductors when there is change in temperature
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semiconductor
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a.c. circuit
Frage 17
Frage
Ohm's law is applicable to
Antworten
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electric arc
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rectifying devices
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gas discharge lamps
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none of these
Frage 18
Frage
Ohm's law can be applied with certain reservations to
Antworten
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rectifying devices
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semiconductors
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electrolytes
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thermionic valves
Frage 19
Frage
The presence of an electric current is made known by
Antworten
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flashing
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effects produced
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cracking
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electric shock
Frage 20
Frage
An electric current can neither be ____ nor ____.
Antworten
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felt, seen
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seen, touched
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seen, produced by any effect
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produced, felt
Frage 21
Frage
The presence of the current is only made known by the effect it produces. Three important effects are
Antworten
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heating, electric shock and generation
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generation, chemical and electric shock
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heating, magnetic and electric shock
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heating, magnetic and chemical
Frage 22
Frage
Voltage applied across a circuit, acts as
Antworten
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mass of electrons
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negative ions
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a component of current
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a force
Frage 23
Frage
In a series circuit the current is
Antworten
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constant
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always zero
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proportional to the resistance
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different from resistors
Frage 24
Frage
In a parallel circuit the potential difference across the resistance
Antworten
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varies
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is different from the applied voltage
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is sometimes constant
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is always constant
Frage 25
Frage
The resistance R1 and R2 are connected in parallel. The ratio of values of resistance R1 : R2 is 4 : 1. The currents in R1 : R2 will be equal to
Antworten
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1 : 4
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1 : 1
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4 : 1
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4 : 4
Frage 26
Frage
A resistance of 4 ohms is connected across 100 V supply. When another resistor 'R' ohms is connected in parallel with 4 ohms, the total current taken from supply was found to be 50 A. The value of resistance 'R' is
Antworten
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2 ohms
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3 ohms
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5 ohms
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4 ohms
Frage 27
Frage
The voltage applied across an electric press was reduced by 50%. The power consumed by the press will be reduced by
Antworten
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25%
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75%
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60%
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50%
Frage 28
Frage
Two electric presses are connected in parallel. The resistance of the first press is 100 ohms and that of the second is 300 ohms. The total current taken by both the presses is 4 A. The ratio of current taken by first : second will be equal to
Antworten
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2 : 3
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1 : 3
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3 : 1
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1.2 : 3
Frage 29
Frage
Three elements having conductance G1. G2 and G3 are connected in parallel. Their combined conductance will be
Antworten
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G1 + G2 + G3
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1/(G1 + G2 + G3)
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(G1G2 + G2G3 + G3G1)/(G1 + G2 + G3)
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1/(1/G1 + 1/G2 + 1/G3)
Frage 30
Frage
Four resistance R1, R2, R3 and R4 are connected in series against 220 V supply. The resistances are such that R1 > R2 > R3 > R4. The least power consumption will be in
Antworten
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resistor R1
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resistor R4
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resistor R3
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resistor R2
Frage 31
Frage
When current flows through heater coil it glows but supply wiring does not glow because
Antworten
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supply wiring is covered with insulation layer
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current through supply line flows at slower speed
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supply wires are made of superior material
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resistance of heater coil is more than that of supply wires
Frage 32
Frage
Resistors commonly used in power circuits are
Antworten
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carbon resistors
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etched circuit resistors
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wire wound resistors
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deposited metal resistors
Frage 33
Frage
International ohm is defined in terms of resistance of
Antworten
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a column of mercury
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a cube of carbon
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unit length of metal wire
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a cube of copper
Frage 34
Frage
Which of the following has negative coefficient of resistance?
Antworten
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wire wound resistor
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non-metals
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thermistor
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metals
Frage 35
Frage
The current carrying capability of the fuse material depends on
Antworten
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length
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material
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cross-sectional area
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all of these
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