A length of wire has a resistance of 10 ohms. What is the resistance of a wire of the same material three times as long and twice the cross-sectional area?
30 ohms
20 ohms
15 ohms
7 ohms
Correct Answer :
C. 15 ohms
Related Questions
What is the practical unit of electrical energy?
Watt
Kilowatt-hour
Kilowatt-second
Megawathour
If the distance between two magnetic poles decreases by 2 timesa the force between them
decreases two times
increases four times
increases two times
decreases four times
How many electrons are needed in the valence orbit to give a material's stability?
When a conductor is stationary and the magnetic field is moving or changing the emf induced is called
Statically induced emf
Mutually induced emf
Self induced emf
Dynamically induced emf
The process by which an emf and hence current is generated or induced in a conductor when there is a change in the magnetic flux linking the conductor is called
Electromagnetic induction
Mutual induction
Faraday's law
Electromagnetic interference
What is the SI unit of specific resistance or resistivity?
Ohm-circular mil per inch
Ohm-circular mil per foot
Ohm-m
Ohm-cm
Mmf in a magnetic circuit corresponds to _____ in an electric circuit
Emf
Voltage drop
Electric Field Intensity
Potential gradient
The amount of magnetizing force to counter balance the resid magnetic material is referred to as
Reluctivity
Susceptivity
Coercivity
Retentivity
One oersted (Oe) is equivalent to _____ Gb/cm.
A law establishing the fact that the algebraic su of the rises and drops of the mmf around a closed loop of a magnetic circuit is equal to zero.
Kirchhoff's circuital law
Maxwell's circuital law
Ampere's circuital law
Coulomb's circuital law
A one cubic cm of copper has how many free electrons at room temperature?
80 × 10^18
8.5 × 10^22
20 × 10^10
50 × 10^20
The force of attraction or repulsion between two magnetic poles is directly proportional to their strengths.
Newton's first law
Faraday's first law of electromagnetic induction
Coulomb's first law
Coulomb's second law
Electric field intensity is measured in
volts/meter
Newton/meter
Newton-meter
Amperes/meter
What is the unit of magnetomotive force?
Volt
Tesla
Ampere- turn
Weber
Calculate the permeability (in T/A. t/m) of a magnetic material that has a relative permeability of 300
3.78 x 10^4
3.78 x 10^-5
3.78 x 10^-3
3.78 x 10^-6
The branch of Engineering which deals with the magnetic effect of electric current is known as
Magnetism
Electromagnetism
Electrical engineering
Electronics engineering
The current of electric circuit is analogous to which quantity of a m
Mmf
Flux
Flux density
R eluctivity
The resistivity of a conductor ___________ with an increase in temperature.
increases
decreases
remains the same
becomes zero
The unit of electrical energy is
Joule
Watt- second
Kilowatt hour
All of these
Whenever a conductor cuts magnetic fluxa an emf is induced in it. This is known as
Coulomb's law
Joule's law
Faraday's law
Ohm's law
Permeance of a magnetic circuit is _________ the cross-sectional area of the circuit.
directly proportional to
inversely proportional to
dependent of
independent of
A substance that attracts pieces iron
Conductor
Semiconductor
Magnet
All of the above
An alloy of 40 percent iron and 60 percent nickel.
Alnico
Permalloy
Hipernik
Manganin
Under ordinary conditionsa a body is considered
positively charged
neutral
negatively charged
stable
What is the usual value of leakage coefficient for electrical machines?
0.5 to 1
1 to 5
5 to 10
1.15 to 1.25
Which of the following is a paramagnetic material?
Carbon
Bismuth
Copper
Oxygen
A positively charged body has
deficit of electrons
excess of neutrons
excess of electrons
deficit of protons
What principle states that each electron in an atom must have a different set of quantum numbers?
Inclusion principle
Exclusion principle
Quantum principle
Electron principle
What is the SI unit of conductivity?
Ohms/m
Ohms-m
Siemens-m
Siemens/m
Two similar polesa each 1Wba placed 1 m apart in air will experience a repulsive force of
63000 N
63 × 10^-3 N
8 × 10^12 N
796 kN