The ratio of the largest to shortest wavelengths in Lyman series of hydrogen spectra is
When the length and area of cross-section both are doubled, then its resistance
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The more readily fissionable isotope of uranium has an atomic mass of
A copper wire of resistance R is cut into ten parts of equal length. Two pieces each are joined in series and then five such combinations are joined in parallel. The new combination will have a resistance
If an electron and a photon propagate in the form of waves having the same wavelength, it implies that they have the same
Which of the following electromagnetic waves have the smallest wavelength?
A capacitor of capacitance 1μF is charged to 1KV. The energy stored in the capacitor in joules is
A 4μF capacitor is charged to 400V. Then its plates are joined through a 100 Ω resistor. The heat produced in the resistor is
The radius of orbit of a planet is two times that of the earth. The time period of planet is
The energy emitted per second by a black body at 27ºC is 10J. If the temperature of the black body is increased to 327ºC, then energy emitted per second will be
The energy supply being cut-off, an electric element cools down to the temperature of its surrounding. But it will not cool further, because
Four blocks of same mass connected by cords are pulled by a force F on a smooth horizontal surface, as shown in figure. The tensions T1, T2 and T3 will be
A particle starts from rest and has an acceleration of 2m − s⁻2 for 10 s. After that, it travels for 30 s with constant speed and then undergoes a retardation of 4 m − s⁻2 and comes back to rest. The total distance covered by the particle is
Four charged particles are projected perpendicularly into the magnetic field with equal speed. Which will have minimum frequency?
A bottle weighing 220 gram and of area of cross-section 50 cm2, and height 4 cm oscillates on the surface of water in vertical position. Its frequency of oscillation is
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A):Doppler effect holds also for electromagnetic waves including microwaves, radio waves and visible light.
Reason(R) : As speed of light is independent of relative motion between source and observer, the formulae for doppler effect are different from that of sound.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): All processes in which pressure and volume are proportional, take place at constant temperature.
Reason(R): Work done in a thermodynamical process is path dependent.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): When we switch on the lights one after the other in our house the main current goes on increasing.
Reason(R): Voltage = current x resistance
If the period of oscillation of mass M suspended from a spring is one second, then the period of 4 M will be
Two discs have same mass and thickness. Their materials have densities d₁ and d₂. The ratio of their moments of inertia about central axis will be
A convex lens of focal length 0.15m is made of a material of refractive index 3/2. When it is placed in a liquid, its focal length is increased by 0.225m. The refractive index of the liquid is
The intensity ratio of the waves is 1 : 16. The ratio of their amplitudes is
A copper block of mass 4 kg is heated in a furnance to a temperature 425ºC and then placed on a large ice block. The mass of ice that will melt in this process will be (Specific heat of copper=500 J-kg⁻1-ºC⁻1 and heat of fusion of ice = 336 kJ-kg⁻1).
The ratio of the slopes of P-V diagrams of adibatic and isothermal processes is
In young's double slit experiment, the intensity of central maximum is I. It one slit is closed, the intensity at the same place will become
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