CURRENT ELECTRICITY

Owen Ryan Ang
Quiz by Owen Ryan Ang, updated more than 1 year ago
Owen Ryan Ang
Created by Owen Ryan Ang over 1 year ago
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Description

A compilation of objective type questions in Electrical Engineering

Resource summary

Question 1

Question
What are the minimum requirements to cause the flow of current?
Answer
  • A voltage source, an ammeter, a conductor and an insulator
  • A voltage source, a switch and a resistor
  • A voltage source and a conductor
  • A voltage source, a conductor and an insulator

Question 2

Question
Out of the following, select the best conductor of electricity.
Answer
  • Graphite
  • China Clay
  • Porcelain
  • None of these

Question 3

Question
Which of the following statements is correct?
Answer
  • The resistance does not play an important role in electrical engineering.
  • The resistance of a wire does not depend upon its material.
  • The resistance of most of the materials is independent of the temperature.
  • The resistance of conductor is the hindrance by which the conductor opposes the flow of the current.

Question 4

Question
Resistance of a conductor increases when
Answer
  • its length increases
  • its area increases
  • both length and area increases
  • specific resistance is kept constant

Question 5

Question
The specific resistance ρ depends upon
Answer
  • The area of cross-section and the length of the conductor
  • The material of the conductor, its area of cress-section and length
  • The nature of the material of the conductor only
  • The area of cross-section of the conductor

Question 6

Question
The specific resistance ρ is defined as
Answer
  • resistance of a conductor which has a length of 1 m and cross-section of 1 m2 at 20C
  • resistance of any conductor at 25C
  • resistance of any conductor at 20C
  • resistance of a conductor which has a length of 1 m and cross-section of 1 cm2 at 20C

Question 7

Question
The resistance of a conductor, when its temperature is increased
Answer
  • remains constant
  • increases
  • varies
  • decreases

Question 8

Question
It was experimentally found by James Prescott Joule that the heat produced in a current carrying conductor is proportional to
Answer
  • the square of the current
  • square of resistance
  • the current
  • inversely proportional to time

Question 9

Question
The value of Joule's mechanical equivalent of heat, J, is equal to
Answer
  • 4.2 calories per Joule
  • 2.4 Joules per calorie
  • 4.2 Joules per calorie
  • 4.2 Joules

Question 10

Question
Temperature coefficient of a conductor is defined as the
Answer
  • increase in resistance per ohm per degree centigrade
  • increase in resistance per degree centigrade
  • increase in resistance per degree absolute
  • decrease in resistance per ohm per degree centigrade

Question 11

Question
When current flows in a conductor, heat is produced because
Answer
  • heat α I²
  • of electronic collision
  • of interatomic collision
  • of Joule's law

Question 12

Question
Heating effect of current has undesirable side effect in
Answer
  • electric oven
  • electric iron
  • immersion heater
  • vacuum cleaner

Question 13

Question
The resistance of carbon (filament in carbon-filament lamps) when its temperature is decreased
Answer
  • increases
  • decreases
  • remains the same
  • increases enormously

Question 14

Question
The curve representing Ohm's law is
Answer
  • a parabola
  • linear
  • sine function
  • a hyperbola

Question 15

Question
The condition in Ohm's law is that
Answer
  • ratio V/I should be constant
  • current should be proportional to voltage
  • the temperature should remain constant
  • the temperature should vary

Question 16

Question
Ohm's law does not apply to
Answer
  • conductors
  • conductors when there is change in temperature
  • semiconductor
  • a.c. circuit

Question 17

Question
Ohm's law is applicable to
Answer
  • electric arc
  • rectifying devices
  • gas discharge lamps
  • none of these

Question 18

Question
Ohm's law can be applied with certain reservations to
Answer
  • rectifying devices
  • semiconductors
  • electrolytes
  • thermionic valves

Question 19

Question
The presence of an electric current is made known by
Answer
  • flashing
  • effects produced
  • cracking
  • electric shock

Question 20

Question
An electric current can neither be ____ nor ____.
Answer
  • felt, seen
  • seen, touched
  • seen, produced by any effect
  • produced, felt

Question 21

Question
The presence of the current is only made known by the effect it produces. Three important effects are
Answer
  • heating, electric shock and generation
  • generation, chemical and electric shock
  • heating, magnetic and electric shock
  • heating, magnetic and chemical

Question 22

Question
Voltage applied across a circuit, acts as
Answer
  • mass of electrons
  • negative ions
  • a component of current
  • a force

Question 23

Question
In a series circuit the current is
Answer
  • constant
  • always zero
  • proportional to the resistance
  • different from resistors

Question 24

Question
In a parallel circuit the potential difference across the resistance
Answer
  • varies
  • is different from the applied voltage
  • is sometimes constant
  • is always constant

Question 25

Question
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
Answer
  • 1 : 4
  • 1 : 1
  • 4 : 1
  • 4 : 4

Question 26

Question
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
Answer
  • 2 ohms
  • 3 ohms
  • 5 ohms
  • 4 ohms

Question 27

Question
The voltage applied across an electric press was reduced by 50%. The power consumed by the press will be reduced by
Answer
  • 25%
  • 75%
  • 60%
  • 50%

Question 28

Question
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
Answer
  • 2 : 3
  • 1 : 3
  • 3 : 1
  • 1.2 : 3

Question 29

Question
Three elements having conductance G1. G2 and G3 are connected in parallel. Their combined conductance will be
Answer
  • G1 + G2 + G3
  • 1/(G1 + G2 + G3)
  • (G1G2 + G2G3 + G3G1)/(G1 + G2 + G3)
  • 1/(1/G1 + 1/G2 + 1/G3)

Question 30

Question
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
Answer
  • resistor R1
  • resistor R4
  • resistor R3
  • resistor R2

Question 31

Question
When current flows through heater coil it glows but supply wiring does not glow because
Answer
  • supply wiring is covered with insulation layer
  • current through supply line flows at slower speed
  • supply wires are made of superior material
  • resistance of heater coil is more than that of supply wires

Question 32

Question
Resistors commonly used in power circuits are
Answer
  • carbon resistors
  • etched circuit resistors
  • wire wound resistors
  • deposited metal resistors

Question 33

Question
International ohm is defined in terms of resistance of
Answer
  • a column of mercury
  • a cube of carbon
  • unit length of metal wire
  • a cube of copper

Question 34

Question
Which of the following has negative coefficient of resistance?
Answer
  • wire wound resistor
  • non-metals
  • thermistor
  • metals

Question 35

Question
The current carrying capability of the fuse material depends on
Answer
  • length
  • material
  • cross-sectional area
  • all of these
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