The path of a magnetic flux in a transformer should have

The path of the magnetic flux in transformer should have

A

high reluctance

B

low reactance

C

high resistance

D

low resistance

When the addenda on pinion and wheel is such that the path of approach and path of recess are half of their maximum possible values, then the length of the path of contact is given by (where r = Pitch circle radius of pinion, R = Pitch circle radius of wheel and $$\varphi $$ = Pressure angle)

A

$$\frac{{\left( {{{\text{r}}^2} + {{\text{R}}^2}} \right)\cos \varphi }}{2}$$

B

$$\frac{{\left( {{{\text{r}}^2} + {{\text{R}}^2}} \right)\sin \varphi }}{2}$$

C

$$\frac{{\left( {{\text{r}} + {\text{R}}} \right)\cos \varphi }}{2}$$

D

$$\frac{{\left( {{\text{r}} + {\text{R}}} \right)\sin \varphi }}{2}$$

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

A

E.M.F.

B

Current

C

Current density

D

Conductivity

Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because

A

Convection becomes important

B

Conduction becomes important

C

Radiation becomes important

D

Sub-cooled boiling occurs

In a particular type of welding, flux is prepared in the form of a coarse powder and granulated flux is spread over the joint. What is this type of welding process called?

A

Electric arc welding

B

Submerged arc welding

C

MIG welding

D

TIG welding

Which of the following is capable of acting both as an acid flux as well as a basic flux in the metal extraction from its ore?

A

Silica

B

Lime

C

Alumina

D

Fluorite

The applied voltage of a certain transformer is increased by 50%, while the frequency is reduced by 50%. The maximum core flux density will

A

become three times

B

become 1.5 times

C

become half

D

remian the same

The value of flux involved m the e.m.f. equation of a transformer is

A

average value

B

r.m.s. value

C

maximum value

D

instantaneous value

The use of higher flux density in the transformer design

A

reduces weight per kVA

B

reduces iron losses

C

reduces copper losses

D

increases part load efficiency

The leakage flux in a transformer depends upon

A

load current

B

load current and voltage

C

load current, voltage and frequency

D

load current, voltage, frequency and power factor

The path of a magnetic flux in a transformer should have

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