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This set of Electromagnetics Multiple Choice Questions & Answers (MCQs) focuses on Electromagnetics Set 12
Q1 | Dielectric strength with increasing thickness
- increases
- decreases
- remains unaltered
- none of the above
Q2 | The property of a capacitor to store electricity is called its
- capacitance
- charge
- energy
- none of the above
Q3 | is that property of a capacitor which delays any change of voltage across it.
- inductance
- capacitance
- potential gradient
- none of the above
Q4 | A capacitance of 100 fiF is connected in series with a resistance of 8000 £2. The timeconstant of the circuit is
- 0.2 s
- 0.4 s
- 0.6 s
- 0.8 s
Q5 | In a cable capacitor, voltage gradient ismaximum at the surface of the
- earth
- conduction
- sheath
- insulator
Q6 | The time constant of an R-C circuit is defined as the time during which capacitorcharging voltage actually rises to percent of its value.
- 37, initial
- 63.2, initial
- 63.2, final
- 37, final
Q7 | The time constant and R-C circuit may also be defined as the time during which thecharging current falls to percent of its initial maximum value,
- 37
- 42
- 63
- 73
Q8 | A capacitor consists of two
- ceramic plates and one mica disc
- insulators separated by a dielectric
- silver-coated insulators
- conductors separated by an insulator
Q9 | Permittivity is expressed in
- farad/sq-m
- farad/metre
- weber/metre
- weber/sq-m
Q10 | What will happen to an insulating medium if voltage more than the breakdownvoltage is applied on it ?
- it will become magnetic
- it will melt
- it will get punctured or cracked
- its molecular structure will get changed
Q11 | Which medium has the least dielectric strength ?
- paraffin wax
- quartz
- glass
- air
Q12 | One volt is the same as
- one joule/coulomb
- one coulomb/joule
- one coulomb
- one joule
Q13 | The capacitance C is charged through a resistance R. The time constant of the chargingcircuit is given by
- cir
- 1/rc
- rc
- ric
Q14 | The bridge used for the measurement of the value of the capacitance is
- wien\s bridge
- wheatstone bridge
- schering bridge
- hay\s bridge
Q15 | If an ohmmeter reading immediately goes practically to zero and stays there, capacitoris
- charged
- short-circuited
- lossy
- satisfactory
Q16 | Out of the following capacitors of identical rating which one will have the smallestdimensions ?
- aluminium foil capacitor
- mica capacitor
- ceramic capacitor
- paper capacitor
Q17 | Mica capacitors are characterised by all of thte following except
- stable operation
- accurate value
- low leakage reactance
- low losses
Q18 | A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. Thestrength of electric field is
- 100 kv/m
- 10 kv/m
- 5 kv/m
- 2 kv/m
Q19 | The ohmmeter reading for a short circuited capacitor is
- infinity
- few kilo ohms
- few megaahms
- zero
Q20 | Which of the following statements is correct ?
- mica capacitors are available in capacitance values of 5 to 20 \\if
- air capapitors have a black band to indicate the outside foil
- electrolytic capacitors must be connected in correct polarity
- ceramic capacitors must be con¬nected in correct polarity
Q21 | Which of the following capacitors preferred for high frequency circuits ?
- air capacitor
- electrolytic capacitor
- mica capacitor
- none of the above
Q22 | An electrolytic capacitor is generally made to provide
- low capacitance
- fixed capacitance
- variable capacitance
- large value of capacitance
Q23 | In order to remove static electricity from machinery
- construct insulated cabins
- insulate the machinery
- ground the framework
- humidify the surroundings
Q24 | If a third equal and similar charge is placed between two equal and similar charges,then this third charge will
- move out of the field of influence of the two charges
- remain in stable equilibrium
- not be in equilibrium
- be in unstable equilibrium
Q25 | A region around a stationary electric charge has
- an electric field
- a magnetic field
- both (a) and (b)
- none of the above