Which of the following is the function of the step-up transformer?
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(a) Low voltage, high current to high voltage and low current (b) Low voltage, low current to high voltage and high […]
In an inductor when current changes from 2 A to 18 A in 0.05 sec, the e.m.f. induced is 20 V. The inductance L is
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(a) 62.5 mH (b) 625 mH (c) 6.25 […]
Energy in a current carrying coil is stored in the form of
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(a) electrical energy (b) magnetic field (c) heat (d) None of these
Correct Answer:
magnetic field
Explanation:
In a current carrying […]
In an LCR circuit, capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to
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(a) 4 L (b) 2 L (c) […]
The material suitable for making electromagnets should have
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(a) High retentivity and high coercivity (b) Low retentivity and low coercivity (c) high retentivity and low coercivity (d) Low retentivity and high coercivity
Radiofrequency choke uses core of
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(a) Air (b) Iron (c) Air and iron (d) None of these
Correct Answer:
Air
Explanation:
Radio frequencies are higher frequencies. Air core chokes are therefore used.
The magnetic flux linked with a circuit of resistance 100Ω increases from 10 to 60 Wb. The amount of induced charge that flows in the circuit is (in coulomb)
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(a) 0.5 (b) 5 […]
The coefficient of mutual inductance of two coils is 6 mH. If the current flowing in one is 2A, the induced e.m.f. in the second coil will be
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(a) Zero (b) 3 V […]
In a primary coil 5 A current is flowing on 220 V. In the secondary coil 2200 V are produced. Ratio of number of turns in secondary coil and primary coil will be
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An oscillator circuit consists of an inductance of 0. mH and a capacitor of 20 μF. The resonant frequency of the circuit is nearly
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(a) 15.92 Hz (b) 159.2 Hz (c) 15.920Hz […]
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