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Let En = -(me^4)/(8ε_0^2 n^2 h^2) be the energy of the nth level of H-atom. If all the H-atoms are in the ground state and radiation of frequency (E2 - E1)/h falls on it, then: (a) it will not be absorbed at all. (b) some of the atoms will move to the first excited state. (c) all atoms will be excited to the n=2 state. (d) no atoms will make a transition to the n=3 state. Choose the correct option:
Consider the following Statements A and B and identify the correct answer: Statement A: For a solar-cell, the I-V characteristics lies in the IV quadrant of the given graph. Statement B: In a reverse-biased pn junction diode, the current measured in ($\mu\text{A}$), is due to majority charge carriers.
A block of mass 4 kg is suspended through two light spring balances A and B connected in series. Then A and B will read respectively:
A piece of ice falls from a height $h$ so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice. The value of $h$ is: [Latent heat of ice is $3.4 \times 10^5 \text{ J/kg}$ and $g = 10 \text{ N/kg}$]
A lift of mass $1000 \text{ kg}$ is moving with an acceleration of $1 \text{ m/s}^2$ in the upward direction. Tension developed in the string, which is connected to the lift, is:
The given graph represents the V-I characteristic for a semiconductor device. Which of the following statements is correct?
A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6A, the voltage across the secondary coil and the current in the primary coil respectively are:
A solid cylinder of mass $2 \text{ kg}$ and radius $4 \text{ cm}$ is rotating about its axis at the rate of $3 \text{ rpm}$. The torque required to stop after $2\pi$ revolutions is:
Three identical spherical shells, each of mass $m$ and radius $r$ are placed as shown in the figure. Consider an axis $XX'$, which is touching two shells and passing through the diameter of the third shell. The moment of inertia of the system consisting of these three spherical shells about the $XX'$ axis is:
In the following circuit, the output Y for all possible inputs A and B is expressed by the truth table:
A solid cylinder of mass $3 \text{ kg}$ is rolling on a horizontal surface with a velocity of $4 \text{ ms}^{-1}$. It collides with a horizontal spring of force constant $200 \text{ Nm}^{-1}$. The maximum compression produced in the spring will be:
The moment of inertia of a thin rod about an axis passing through its mid-point and perpendicular to the rod is $2400\text{ g cm}^2$. The length of the $400\text{ g}$ rod is nearly:
A solid sphere is in rolling motion. In rolling motion, a body possesses translational kinetic energy ($K_t$) as well as rotational kinetic energy ($K_r$) simultaneously. The ratio $K_t : (K_t + K_r)$ for the sphere will be:
A standard filament lamp consumes 100 W when connected to a 200 V AC mains supply. The peak current through the bulb will be:
The net impedance of the circuit (as shown in the figure) will be:
A black body at $227^\circ\text{C}$ radiates heat at the rate of $7 \text{ cal cm}^{-2}\text{s}^{-1}$. At a temperature of $727^\circ\text{C}$, the rate of heat radiated in the same units will be:
An energy of $484 \text{ J}$ is spent in increasing the speed of a flywheel from $60 \text{ rpm}$ to $360 \text{ rpm}$. The moment of inertia of the flywheel is:
An object flying in the air with velocity $(20\hat{i} + 25\hat{j} - 12\hat{k})$ suddenly breaks into two pieces whose masses are in the ratio of $1:5$. The smaller mass flies off with a velocity $(100\hat{i} + 35\hat{j} + 8\hat{k})$. The velocity of the larger piece will be:
The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561 Å. The wavelength of the second spectral line in the Balmer series of singly ionized helium atom is:
In which of the following devices, the eddy current effect is not used?