The electrons in the last orbit of an atom are called _______ electrons.
free
valence
bound
thermionic
Correct Answer :
B. valence
Related Questions
The hot resistance of an incandescent lamp is about _______ its cold resistance.
10 times
100 times
5 times
50 times
A magnetic field is
The current flow through space around a permanent magnet
The force set up when current flows through a conductor
The force that drives current through a resistor
The force between the plates of a charged capacitor
Magnetic field intensity is a ________ quantity.
scalar
phasor
vector
variable
Germanium atom has ______ protons and ______ electrons.
32, 32
32, 42
42, 32
34, 34
Used to maintain strength of magnetic field
Container
Air gap
Keeper
S ource
Whenever a flux inking a coil or current changesa an emf is induced in it. This is known as
Joule's Law
Coulomb's Law
Faraday's first law of electromagnetic induction
Faraday's second law of electromagnetic induction
Why is it that the magnitude of magnetomotive force required for air gap is much greater than that required for iron part of a magnetic circuit?
Because air is a gas
Because air has the highest relative permeability
Because air is a conductor of magnetic flux
Because air has the lowest relative permeability
The magnetic flux through a wire loop in a magnetic field does not d
T he area of the loop
The magnitude of the field
The shape of the loop
The angle between the plane of the loop and the direction
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
Which of the following materials has the least hysteresis loop area?
soft iron
silicon steel
hard steel
wrought iron
The temperature coefficient of resistance of conductors is
positive
zero
negative
infinite
Hysteresis is a phenomenon of _________ in a magnetic circuit.
setting up constant flux
lagging of H behind B
lagging B behind H
leading B ahead H
An effect which is generally used in the gausameter to measure flux density.
Skin effect
Magnetic effect
Hall effect
Flywheel effect
A good conductor has how many valence electrons?
Which of the following electric quantities is vector in character?
Field
Charge
Energy
Potential Difference
What is the SI unit of reluctance?
At
At/m
N/Wb
At/Wb
One weber of flux is equal to _______ magnetic lines of force.
10^6
10^10
4 × 10^7
10^8
The branch of Engineering which deals with the magnetic effect of electric current is known as
Magnetism
Electromagnetism
Electrical engineering
Electronics engineering
When the relative permeability of a material is slightly more than 1a it is called ______ material.
diamagnetic
ferromagnetic
paramagnetic
non-magnetic
What is the value of the absolute permittivity of air?
8.854 F/m
8.854 × 10^-12 mF/m
8.854× 10^-12 F/m
8.854 × 10^-12 F/m
When the ferromagnetic substance is inserted in a current- carrying solenoida the magnetic field is
Greatly decreased
Greatly increased
Slightly decreased
Slightly increased
Flux density is measured in
Tesia
Weber
Ampere- turn
Maxwell
A test charge means a charge of
-1 C
1 electron
+1 C
-20 C
What is the typical saturation flux density for most magnetic materials?
4 Wb/m^2
5 Wb/m^2
1 Wb/m^2
2 Wb/m^2
The force between two magnetic poles is _____ their poles strength.
equal to
directly proportional to
inversely proportional to
directly proportional to the square root of
The emission of electrons from hot bodies is called
Radiation effect
Edison effect
Skin effect
Half effect
If on looking at any one end of a solenoid; the direction of current flow is found to be clockwise then the end under observation is a south pole. This is known as
Right hand rule
Left hand rule
Cork screw rule
End Rule
What is the SI unit of conductance?
Siemens
Mhos
Ohms
1/Ohms
Who demonstrated that there are magnetic effects around every current-carrying conductor and that current-carrying conductors can attract and repel each other just like magnets?
Luigi Galvani
Hans Christian Oersted
Charles Coulomb
Andre Ampere
Electric field intensity is a ________.
scalar
phasor
vector
variable