Two metal wires of identical dimensions are connected in series. If σ₁ and σ₂ are the conductivities of the metal wires respectively, the effective conductivity of the combination is
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(a) σ₁+ σ₂/σ₁ […]
The young’s modulus of steel is twice that of brass. Two wires of same length and of same area of cross section, one of steel and another of brass are suspended from the same roof. […]
The value of coefficient of volume expansion of glycerin is 5 x 10⁻⁴ k⁻¹. The fractional change in the density of glycerin for a rise of 40⁰ C in its temperature, is
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The heart of a man pumps 5 litres of blood through the arteries per minute at a pressure of 150mm of mercury. If the intensity of mercury be 13.6 x 10³ kg/m³ and g=10 m/s² […]
The energy of the em waves is of the order of 15 keV. To which part of the spectrum does it belong?
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(a) ultraviolet rays (b) γ-rays (c) X-rays (d) Infra-red rays
Correct […]
The cylindrical tube of a spray pump has radius R, one end of which has n fine holes, each of radius r. If the speed of the liquid in the tube is V, the speed […]
The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is -20⁰C, the temperature of the surroundings to which it rejects heat is
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(a) 11⁰C (b) 21⁰C (c) […]
Point masses m₁ and m₂ are placed at the opposite ends of a rigid rod of length L, and negligible mass. The rod is to be set rotating about an axis perpendicular to it. The […]
On a frictionless surface, a block of mass M moving at speed v collides elastically with another block of same mass M which is infinitely at rest. After collision the first block moves at an […]
Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is
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(a) ≥2.8×10⁻⁹ m (b) ≤2.8×10⁻¹² m (c) < […]
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