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A coil of self-inductance L is connected in series with a bulb B and an AC source. The brightness of the bulb decreases when:
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:
If the radius of the earth is suddenly contracted to half of its present value, then the duration of the day will be of:
Four identical thin rods each of mass $M$ and length $t$, form a square frame. Moment of inertia of this frame about an axis through the centre of the square and perpendicular to its plane is:
The instantaneous values of alternating current and voltages in a circuit are given as $i = \frac{1}{\sqrt{2}} \sin(100\pi t)$ ampere and $e = \frac{1}{\sqrt{2}} \sin(100\pi t + \pi/3)$ volt. The average power in Watts consumed in the circuit is:
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:
A solid sphere is rotating about a diameter at an angular velocity $\omega$. If it cools so that its radius reduces to $\frac{1}{n}$ of its original value, its angular velocity becomes:
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 peak voltage of the AC source is equal to:
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:
An AC source is connected to a capacitor C. Due to a decrease in its operating frequency:
An AC source given by $V = V_m \sin(\omega t)$ is connected to a pure inductor $L$ in a circuit and $I_m$ is the peak value of the AC current. The instantaneous power supplied to the inductor is:
A horizontal platform is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time a viscous fluid of mass $m$ is dropped at the centre and is allowed to spread out and finally fall. The angular velocity during this period:
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 black body is at a temperature of $5760\text{ K}$. The energy of radiation emitted by the body at a wavelength of $250\text{ nm}$ is $U_1$, at a wavelength of $500\text{ nm}$ is $U_2$ and that at $1000\text{ nm}$ is $U_3$. Given Wien's constant $b=2.88 \times 10^6\text{ nm K}$, which of the following is correct?
The net impedance of the circuit (as shown in the figure) will be:
An AC source is connected to the given circuit. The value of $\phi$ will be:
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:
The M.I. of a body about the given axis is $1.2 \text{ kg m}^2$. Initially, the body is at rest. In order to have a rotational kinetic energy of 1500 J, an angular acceleration of $25 \text{ rad/s}^2$ must be applied about that axis for a duration of:
Consider a system of two particles having masses $m_1$ and $m_2$. If the particle of mass $m_1$ is pushed towards the centre of mass of particles through a distance $d$, by what distance would the particle of the mass $m_2$ move so as to keep the centre of mass of particles at the original position?