The hot resistance of an incandescent lamp is about _______ its cold resistance.
10 times
100 times
5 times
50 times
Correct Answer :
A. 10 times
Related Questions
When the relative permeability of a material is much greater than 1a it is called _______ material.
diamagnetic
ferromagnetic
paramagnetic
non-magnetic
The resistivity of a conductor ___________ with an increase in temperature.
increases
decreases
remains the same
becomes zero
When a wire loop is rotated in a magnetic field the direction of the induced emf changes one in every _______ revolution
What is the SI unit of conductivity?
Ohms/m
Ohms-m
Siemens-m
Siemens/m
One ampere- turn is equivalent to _____ gilberts
One farad equals
1 coulomb/volt
1 newton/coulomb
1 newton-meter
1 volt/second/ampere
What is the cgs unit of magnetomotive force?
Gilbert
Ampere- turn
Maxwell
Weber
Who developed the electromagnetic theory of light in 1862?
Heinrich Rudolf Hertz
Wilhelm Rontgen
James Clerk Maxwell
Andre Ampere
Which of the following is a natural magnet?
Steel
Magnesia
Lodestone
S oft iron
The core of a transformer heats up when its primary is fed from an ac source because of
permeability
ferromagnetism
reluctance of core
hysteresis loss
The potential at a point due to a charge is 15 V. If the distance is times, the potential at the point will be
5 V
18 V
45 V
15 V
A magnetic pole produces 5000 field lines. How much is the flux in webers? A. 50 × 10^-6
5 × 10^-6
500 × 10^-6
500 × 10^-5
The emission of electrons from hot bodies is called
Radiation effect
Edison effect
Skin effect
Half effect
__________ is a substance of whose molecules consist of the same kind of atom.
Mixture
Compound
Element
Isotope
Defined as the number of lines per unit area through any substance in a plane at right angles to the lines of force
Flux
Flux lines
Flux density
Flux intensity
The force between two magnetic poles is _______ their pole strengths.
directly proportional to
the sum of
inversely proportional to
the product of
A negatively charge body has
deficit of electrons
excess of protons
excess of electrons
deficit of neutrons
Who discovered that a current-carrying conductor would move when placed in a magnetic field?
Michael Faraday
Andre Ampere
Hans Christian Oersted
Gustav Robert Kirchhoff
Referred to as the specific reluctance of a material
Resistivity
Reluctivity
Conductivity
Permeability
Bonding of atoms that is due to the force of attraction between positive ions and a group of negative ions
Ionic bond
Covalent Bond
Electrostatic Bond
Metallic bond
One coulomb of charge consists of ________ electrons.
624× 10^16
62.4 × 10^16
6.24 × 10^16
0.624 × 10^16
Magnetic intensity is a
Phasor quantity
Physical quantity
Scalar quantity
Vector quantity
Magnetic field intensity is a ________ quantity.
scalar
phasor
vector
variable
Hipernik is an alloy containing __________ iron and __________ nickel.
40% ; 60%
60% ; 40%
50% ; 50%
70% ; 30%
It is the reciprocal of reluctance and implies the case of readiness with which magnetic flux is developed.
R esistance
Conductance
Permeance
I nductance
Electric field intensity is a ________.
scalar
phasor
vector
variable
When the current flowsa the magnetic field ��. conductor is in what direction?
The same as the current direction
Opposite the current direction
Omnidirectional
In the direction determined by the left hand rule
The emf produced in a wire by its motion across a magnetic field does not depend upon the
Diameter of the wire
Length of the wire
Orientation of the wire
Flux density of the field
The temperature coefficient of resistance of semiconductors is
positive
zero
negative
infinite
Defined as a closed path in which magnetic induction or flux flows
Electric circuit
Magnetic circuit
Electronic circuit
Electromagnetic circuit