All matters (gasa liquid and solid) are composed of
Neutrons
Particles
Electrons
Atoms
Correct Answer :
D. Atoms
Related Questions
What is the measure of the density and sign of the electric charge at a point relative to that at some time?
Electric potential
Electric charge
Electric current
Electric intensity
States that the ratio of the thermal conductivity is proportional to the absolute temperature for all metals.
Wien's displacement law
Hartleys law
Hall's law
Wiedemann Franz law
A negatively charge body has
deficit of electrons
excess of protons
excess of electrons
deficit of neutrons
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
If the value of 25 of a conductor is 1/230 per oCa then the value of 0is
1/180 peroC
1/150 per oC
1/280 per oC
1/230 per oC
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
If a magnetic flux cuts across 200 turns at a rate of 2Wb/sa the induced voltage according to Faraday's law is about
400 V
100 V
200 V
600 V
The emission of electrons from hot bodies is called
Radiation effect
Edison effect
Skin effect
Half effect
Temporary magnets are commonly employed in
electric instruments
motors
moving coils loudspeakers
magnetos
Which of the following statements is TRUE?
Silicon dioxide is a good
The current carriers in conductors are valence electrons
For conductorsa the valence electron are strongly attracted to the nucleus
The valence electrons are located in the nucleus of an atom
One coulomb of charge consists of ________ electrons.
624× 10^16
62.4 × 10^16
6.24 × 10^16
0.624 × 10^16
The magnetic potential in a magnetic circuit can be measured in terms of
Mmf
Emf
Farad
Coulomb
Which of the following materials has the highest dielectric strength?
Glass
Oiled paper
Mica
Air
The temperature coefficient of resistance of conductors is
positive
zero
negative
infinite
What is the SI unit of conductivity?
Ohms/m
Ohms-m
Siemens-m
Siemens/m
A good conductor has how many valence electrons?
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 mass of proton is __________ the mass of an electron.
equal to
about 1837 times
less than
200 tim es
What bond is formed when electrons in the outermost energy orbits of the atoms are shared between two or more electrons?
Ionic
Covalent
Metallic
Van der Waals
What revolves about the positive nucleus in a definite orbit?
Atom
Proton
Electron
Neutron
______ is an electromagnet with its core in the form of a close magnetic ring.
S olenoid
Paraboloid
Toroid
Cycloid
The point in a magnet where the intensity of magnetic lines of force is maximum
Magnetic pole
South pole
North pole
Unit pole
Which of the following is a vector quantity?
Magnetic potential
Magnetic field intensity
Magnetic permeability
F lux density
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
Lenz' law states that the direction of the induced emf and hence current
Is determined by the rate of current flux
Is found by the right hand rule
Is found by the left hand rule
Always opposes the cause producing it
Residual magnetism refers to the flux densitya which exists in the iron core when the magnetic field intensity is
Minimized
Reduced to zero
Maximize
Unity
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 temperature coefficient of resistance of semiconductors is
positive
zero
negative
infinite
Electric field intensity is measured in
volts/meter
Newton/meter
Newton-meter
Amperes/meter
What type of bond is formed when there exists some form of collective interactions between the (negatively charged) electrons and (positively charged) nuclei in a solid?
Ionic
Covalent
Metallic
Van der Waals