EE part 1

mutual inductance and self inductance of the two coils

The coefficient of coupling between two air core coils depends on

N(theta) / I

The coefficient of self-inductance of a coil is defined as

the temperature should remain constant

The condition in Ohm's law is that

the degree of magnetic linkage

The coupling coefficient denotes

yeap

The current carrying capacity of the fuse material depends on length, material and cross-sectional area?

linear

The curve representing Ohm's law is that

it does not affect the constant direct current

The effect of the inductance of a coil on a constant direct current is that

False

The flux linked with a coil of inductance L carrying current i is d/dt (Li)

in inverse proportion to the square of the distance

The force between two magnetic poles varies with distance between them. The variation is

exponential law

The growth of current in an inductive circuit follows

Lenz

The law that induces emf and current always opposes the cause producing them was discovered by

current, magnetic field and direction of force on a conductor

The left hand rule correlates

G1 + G2 + G3

Three elements having conductance G1, G2 and G3 are connected in parallel. Their combine conductance will be

soft iron

A material commonly used for shielding or screening magnetism is

lodestone

A natural magnet is called

tends to oppose the decay of coil current

A collapsing field around the coil

zero

A conductor of length L has current I passing through it, when it is placed parallel to a strong magnetic field. the force experienced by the conductor will be

demagnetizing metallic part

A degaussing is the process of

nickel, cobalt and steel

A magnet is able to attract

4 ohms

A resistance of 4 ohms is connected across 100 volt supply. When another resistor is connected in parallel with 4 ohms, the total current taken from supply was found to be 50A. The value of resistance R is

8.854 x 10^-12 farad/meter

Absolute permittivity of vacuum is taken as

always opposes the cause producing it

According to Lenz's law the direction of induced emf and hence current

B^1.6

According to hysteresis law, hysteresis loss in a material is proportional to

core saturation

Air gap in the iron core of an inductor prevents

seen or touched

An electric current can neither be

K = M / square root of L1l2

Coupling coefficient k, a term much used in radio work can be obtained from

curie temperature

Each ferromagnetic material has characteristic temperature above which its properties are quite different from those below that temperature. This temperature is called

increasing the resistance of magnetic medium

Eddy current loss can be minimized by

1/2 LI^2 joules

Energy stored in an inductance is given by

north to south

Externally, magnetic line of force travels

semiconductor

Ferrimagnetic materials generally behave as a

resistor R4

Four resistances R1, R2, R3, 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

inductance of the coil

Good smoothing factor of a coil depends on the

vacuum cleaner

Heating effect of current has undesirable side effect in

using grain oriented silicon steel

Hysteresis loses can be reduced by

is always constant

In a parallel circuit the potential difference across the resistance

constant

In a series circuit the current

eddy current loss

In electrical machines, laminated cores are used with a view of reducing

direction of force on conductor

In the left hand rule, thumb always represents

paramagnetic material

Interaction between the neighboring dipoles is negligible in case of a

a column of mercury

International ohm is defined in terms of resistance of

near to one end of a magnet

Iron becomes magnetized by induction when its

low permeability

It is difficult to magnetize steel because it is

the square of the current.

It was experimentally found by James Prescott Joule that the heat produced in a current-carrying conductor is proportional to

4.2 Joules per calories

Joule's mechanical equivalent of heat, J, is equal to

more than unity

Leakage factor is

flux

Magnetic lines of force are called

A voltage source and a conductor

Minimum requirements to cause the flow of current.

M = N2 (dtheta) / dt

Mutual Inductance can also be defined as

semiconductor

Ohm's Law does not apply to

electrolytes

Ohm's law can be applied with certain reservations to

nawp

Ohm's law is applicable to electric arc, gas discharge lamps and rectifying devices?

conductance

Permeance is analogous to

1 + k/µo

Relative permeability of a material is given by (K is susceptibility of the material)

Its length increases.

Resistance of a conductor increases when

wire wound resistors

Resistors commonly used in power circuits

inductance

Sparking occurs when a load is switched off because the circuit has high

The resistance of conductor is the hindrance by which the conductor opposes the flow of current.

Statement that is correct.

increase in resistance per ohm per degree centrigade

Temperature coefficient of a conductor is defined as the

J / m^3 / s

The area of hysteresis loop represents hysteresis loss in

Graphite

The best conductor of electricity.

soft magnetic materials

The magnetic materials which can be easily magnetized in both directions are known as

M.M.F

The magnetic potential in a magnetic circuit can be measure in terms of

residual

The magnetism that remains in a magnet after the magnetizing force has been removed is called

electrons orbital motion, spin of the nucleus about its axis and electron spin

The magnetization in any magnetic material appears as a result of

touching each other

The mutual inductance of two coils is maximum when the coils are

the conductivity of a material for magnetic lines of force

The permeability of a material means

effects produced

The presence of an electric current is made known by

heating, magnetic and electric shock

The presence of the current is only made known by the effect produces. Three important effects are

B / µoH

The relative permeability (µr) is given by

slightly greater than 1

The relative permeability of paramagnetic substance is

5000

The relative permeability µ for iron is

1:4

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

increases

The resistance of carbon when its temperature is decreased

The nature of the material of the conductor only.

The specific resistance p depends upon

resistance of a conductor which has a length of 1m and cross section of 1m squared at 20 degrees celcius

The specific resistance p is defined as

magnetization

The sum of the magnetic moments in unit volume of the solid is called

L/R

The time constant of an inductive circuit is defined as the ratio of

63% of its final steady state value

The time constants is the time it takes the current in an inductive circuit to rise to

Square root of L1L2

The value of mutual inductance in term of self inductance of the two coils L1 and L2 is proportional to

4π x 10^-7 Hm^-1

The value of permeability for the free space is

75%

The voltage applied across an electric press was reduced by 50%. The power consumed by the press will be reduced by

ferrites

Transformer cores operating at microwave frequency ranges are generally made up of

3:1

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 4A. The ratio of current taken by first: second will be equal to

a force

Voltage applied across a circuit acts as

of interatomic collision

When current flows in a conductor, heat is produced because

resistance of heater coil is more than that of supply wires

When current flows through heater coil it glows but supply wiring does not glow because

Increases

When its temperature is increased, the resistance of a conductor

True

When steel torodial ring is magnetized by passing current through its coil, it develops no magnetic poles

magnetic flux density = flux / area

When the magnetic flux and the area under its influence are known, the magnetic flux density can be given as

Faraday's Law

Whenever a conductor cuts magnetic flux, an emf is induced in that conductor. This statement is due to

thermistor

Which of the following has negative coefficient of resistance?

supermalloy

Which of the following has the highest value of relative permeability

Coefficient of coupling for tightly coupled coil is zero

Which of the following is correct?

magnetic field intensity

Which of the following is vector quantity

carbon steel, platinum cobalt and alnico v

Which of the following material is used for making permanent magnets

diamagnetic

Which of the following materials does not have permanent magnetic dipole

Inductance characterizes the magnetic properties of a coil which are significant for the value of self induced voltage generated due to current change in the coil.

Which of the following statements about inductance of a coil is true?

current

While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electric circuit?

flux and current flow

While comparing magnetic and electric circuits, the point of dissimilarity exists while considering