A cylindrical capacitors has charge Q and length L. If both the charge and length of the capacitors are doubled, by keeping other parameters fixed, the energy stored in the capacitor
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(a) […]
A capacitor having a capacity of 2 μF is charged to 200V and then the plates of the capacitor are connected to a resistance wire. The heat produced in joule will be
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A tuned amplifier circuit is used to generate a carrier frequency of 2 MHz for the amplitude modulation. The value of √LC is
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(a) 1/2πx10⁶ (b) 1/2×10⁶ (c) 1/3πx10⁶ (d) 1/4πx10⁶
Correct […]
A common emitter amplifier is designed with n-p-n transistor (α=0.99). The input impedence is 1kΩ and load is 10kΩ. The voltage gain will be
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(a) 9900 (b) 99 (c) 9.9 (d) 990
Correct […]
A horizontal straight conductor kept in north-south direction falls under gravity. Then
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(a) No e.m.f. is induced along the length of conductor (b) A current will be induced from south to north […]
A coil of N turns and mean cross-sectional area A is rotating with uniform angular speed ω about an axis at right angle to uniform magnetic field B. The induced e.m.f. E in the coil […]
Electrons in a certain energy level n=n₁, can emit 3 spectral lines. When they are in another energy level, n=n₂. They can emit 6 spectral lines. The orbital speed of the electrons in the two […]
In a laser tube, all the photons
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(a) have same energy (b) have same wavelength (c) move in same direction (d) move with same speed
Correct Answer:
move with same speed
Explanation: […]
An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is
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(a) (E/2m)¹∕₂ (b) c(2mE)¹∕₂ (c) 1/c (2m/E)¹∕₂ (d) 1/c (E/2m)¹∕₂
Correct Answer: […]
Three resistances 2Ω, 3Ω and 4Ω are connected in parallel. The ratio of currents passing through them when a potential difference is applied across its ends will be
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(a) (5:4:3) (b) (6:3:2) […]
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