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Which of the following materials is generally used in the design of electromagnetic machines?
Answer: c Explanation: Ferromagnetic materials can strongly act like a magnet when placed in a magnetic field. They are exhibited by materials such as iron, cobalt, nickel, etc. Ferromagnetic materials are generally used in electromagnetic machines.
Answer: c
Explanation: Ferromagnetic materials can strongly act like a magnet when placed in a magnetic field. They are exhibited by materials such as iron, cobalt, nickel, etc. Ferromagnetic materials are generally used in electromagnetic machines.
See lessWhich of the following circuit is designed to dissipate heat produced in the machine?
Answer: d Explanation: A thermal circuit in electrical machine design deals with the mode and media to dissipate heat produced in the machine. The heat produced in the machine leads to losses.
Answer: d
Explanation: A thermal circuit in electrical machine design deals with the mode and media to dissipate heat produced in the machine. The heat produced in the machine leads to losses.
See lessCalculate the convection current when electron density of 200 units is travelling at a speed of 12m/s.
Answer: b Explanation: The convection current density is given by, J = ρeV J = 200 X 12= 2400 units
Answer: b
See lessExplanation: The convection current density is given by, J = ρeV
J = 200 X 12= 2400 units
Find the conduction current density when conductivity of a material is 500 units and corresponding electric field is 2 units.
Answer: c Explanation: The conduction current density is given by, J = σE J = 500 X 2 = 1000 units.
Answer: c
See lessExplanation: The conduction current density is given by, J = σE
J = 500 X 2 = 1000 units.
The current flowing through an insulating medium is called
Answer: b Explanation: A beam of electrons in a vacuum tube is called convection current. It occurs when current flows through an insulating medium like liquid, vacuum etc.
Answer: b
See lessExplanation: A beam of electrons in a vacuum tube is called convection current. It occurs when current flows through an insulating medium like liquid, vacuum etc.
For conductors, the free electrons will exist at
Answer: d Explanation: In conductors, the free electrons exist in the conduction band. Since the band gap energy is very low, less energy is required to transport the free electrons to the conduction band, as they are readily available to conduct.
Answer: d
See lessExplanation: In conductors, the free electrons exist in the conduction band. Since the
band gap energy is very low, less energy is required to transport the free electrons to the conduction band, as they are readily available to conduct.
Alternating current measured in a transmission line will be
Answer: c Explanation: The instantaneous current flowing in a transmission line, when measured using an ammeter, will give RMS current value. This value is 70.7% of the peak value. This is because, due to oscillations in AC, it is not possible to measure peak value. Hence to normalise, we consider cRead more
Answer: c
See lessExplanation: The instantaneous current flowing in a transmission line, when measured using an ammeter, will give RMS current value. This value is 70.7% of the peak value. This is because, due to oscillations in AC, it is not possible to measure peak value. Hence to normalise, we consider current at any time in a line will be the RMS current.
Find the band gap energy when a light of wavelength 1240nm is incident on it.
Answer: a Explanation: The band gap energy in electron volt when wavelength is given is, Eg = 1.24(μm)/λ = 1.24 x 10-6/1240 x 10-9 = 1eV.
Answer: a
See lessExplanation: The band gap energy in electron volt when wavelength is given is, Eg =
1.24(μm)/λ = 1.24 x 10-6/1240 x 10-9 = 1eV.
Conduction in metals is due to
Answer: a Explanation: Conduction in metals is only due to majority carriers, which are electrons. Electrons and holes are responsible for conduction in a semiconductor.
Answer: a
See lessExplanation: Conduction in metals is only due to majority carriers, which are electrons.
Electrons and holes are responsible for conduction in a semiconductor.
Find the range of band gap energy for conductors.
Answer: b Explanation: Conductors are materials with least band gap energy. The smallest range in this group is 0.2-0.4 eV.
Answer: b
See lessExplanation: Conductors are materials with least band gap energy. The smallest range
in this group is 0.2-0.4 eV.