A Wheatstone bridge can measure any resistance, but it only has a small range. High and low resistances will make the choice of galvanometer harder, and the response less linear. Moreover, while measuring low resistances, the resistance of copper strips and the connecting wires become comparable to the unknown low resistance and hence cannot be neglected. Hence Wheatstone bridge is used to measure the value of medium resistance.
Ques 92. Diffusion Capacitance of a PN junction diode ________ with forward bias.
May increase or decrease
The diffusion capacitance occurs due to the stored charge of minority electrons and minority holes near the depletion region. Diffusion capacitance is also sometimes referred to as storage capacitance.
When a P-N junction is forward biased, a capacitance that is much larger than the transition capacitance comes into play. This type of capacitance is called Diffusion Capacitance. Diffusion capacitance occurs due to the stored charge of minority electrons n minority holes near the depletion region. when the width of depletion region decreases ,then diffusion capacitance increases
Ques 93. While selecting a heating element, one should keep in mind that its specific resistance should be
As low as possible
The resistance of a material having unit length and the unit cross-sectional area is known as Specific Resistance or Resistivity. Therefore material should have high specific resistance so that we can use a small quantity of wire to get the required amount of heat.
Ques 94. The resisting capacity of the Vacuum circuit breaker is
Lower as compared to others
In comparison to various other insulating media in use in circuit breakers, vacuum circuit breaker is the superior dielectric strength.Dielectric materials are essentially insulators, which means that no current will flow through the material when a voltage is applied. The dielectric strength of the vacuum circuit breaker is better than all other breakers except air and SF6 gas which are generally employed at high pressure.
Ques 95. Surge diverters and Surge absorbers are the types of
Overvoltage protection devices✔
The surge absorber and surge diverters are types of overvoltage protection that limit the transient overvoltage and switching overvoltages.
The steepness of the wavefront of traveling waves can cause damage to the apparatus in addition to the magnitude of the wave. The more steeper is the traveling wave, the more is damage to the apparatus. Thus to reduce the steepness of the wavefront of the surge, a surge absorber is used.
The surge absorber is a protective device that can reduce the steepness of the wavefront of a surge and absorbs energy contained in a travailing waves. Though surge diverter and surge absorber eliminate the surge, the way in which it is done is different on the two devices. The surge diverter diverts the surge to the earth while the surge absorber absorbs energy contained in the surge.
Ques 96. The 400 V distribution lines are commonly known as
The 400 V distribution lines (usually known as distributors) are laid along the roads and service connections to consumers are tapped oﬁ’ from the distributors.
At the local distribution centers, there are step-down distribution transformers. The voltage level of 6.6 kV, 11 kV is further reduced to 400 V using distribution transformers.
Sometimes it may be reduced to 230 V. The power is then transmitted using distributors and service mains to the consumers. This is secondary distribution, also called low voltage distribution.
Ques 97. Which of the following has the least power consumption?
CFLs use 25-35% of the energy used by incandescent bulbs, but if you really want to make the biggest environmental impact on the environment, choosing LEDs is the way to go. Residential LEDs use 75% less energy and last 25 times longer than incandescent lighting.
Ques 98. Ceramics do not possess
High melting point
A ceramic is an inorganic compound, non-metallic, solid material comprising metal, non-metal or metalloid atoms primarily held in ionic and covalent bonds. Since ceramics is non-metallic material, therefore, it does not conduct electricity.
Ques 99. 0110 in binary form can be written as _____________ in decimal form.
Conversion from Binary to Decimal
Expand the number given in the binary form in the power of 2 and sum the values, the result which we will get will be in decimal form.
Ques 100. The given figure represents _________ lighting system
In this method, the light does not reach the working plane directly from the lamps. It is all reﬂected on the walls and ceiling from where it is indirectly reached to the working plane. This is called as diffused reﬂection. In this 0 to 10 % of light is in the lower hemisphere and 90 to 100 % is in the upper hemisphere. The advantage of this method is it gives no shadows and no glare. It is used in shops, hotels. drawing offices and workshops.