When an α-particle of mass m moving with velocity ν bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on m as
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(a) 1/√m […]
Given the value of Rydberg constant is 10⁷ m⁻¹, the wave number of the last line of the Balmer series in hydrogen spectrum will be
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(a) 0.5×10⁷ m⁻¹ (b) 0.25×10⁷ m⁻¹ (c) […]
An inductor 20 mH, a capacitor 50 μF and a resistor 40Ω are connected in series across a source of emf V=10 sin340t. The power loss in AC circuit is
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(a) 0.67 […]
A small signal voltage V(t)=V₀ sin ωt is applied across an ideal capacitor C
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(a) over a full cycle the capacitor C does not consume any energy from the voltage source (b) […]
A linear aperture whose width is 0.02 cm is placed immediately in front of a lens of focal length 60 cm. The aperture is illuminated normally by a parallel beam of wavelength 5×10⁻⁵ cm. The […]
A bar magnet is hung by a thin cotton thread in a uniform horizontal magnetic field and is in equillibrium state. The energy required to rotate it by 60⁰ is W. Now the torque required […]
A n-p-n transistor is connected in common emitter configuration in a given amplifier. A load resistance of 800Ω is connected in the collector circuit and the voltage drop across it is 0.8 V. If the […]
The half-life of a radioactive substance is 30 min. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is
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(a) 15 (b) 30 (c) 45 […]
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: […]
A long straight wire of radius a carries a steady current I. The current is uniformly distributed over its cross-section. The ratio of the magnetic field B and B’ at radial distances a/2 and 2a […]
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