Question Bank Directory

A transistor-oscillator using a resonant circuit with an inductance L (of negligible resistance) and a capacitance C has a frequency f. If L is doubled and C is changed to 4C, the frequency will be:

A 10 $\mu$F capacitor is connected to a 210 V, 50 Hz source. The peak current in the circuit is nearly ($\pi = 3.14$):

A spring of force constant $k$ is cut into lengths of ratio $1:2:3$. They are connected in series and the new force constant is $k'$. If they are connected in parallel and force constant is $k''$, then $k':k''$ is:

A car of mass $1000 \text{ kg}$ negotiates a banked curve of radius $90 \text{ m}$ on a frictionless road. If the banking angle is $45^{\circ}$, the speed of the car is:

The mass of a lift is $2000 \text{ kg}$. When the tension in the supporting cable is $28000 \text{ N}$, then its acceleration is: (Take $g=10 \text{ m/s}^2$)

A gramophone record is revolving with an angular velocity $\omega$. A coin is placed at a distance $r$ from the centre of the record. The static coefficient of friction is $\mu$. The coin will revolve with the record if:

Two stones of masses $m$ and $2m$ are whirled in horizontal circles, the heavier one in a radius $r/2$ and the lighter one in the radius $r$. The tangential speed of lighter stone is $n$ times that of heavier stone when they experience the same centripetal forces. The value of $n$ is:

Find the maximum velocity for skidding for a car moving on a circular track of radius 100 m. The coefficient of friction between the road and tyre is 0.2.

A cyclist turns around a curve at $15 \text{ miles/hour}$. If he turns at double the speed, the tendency to overturn is:

In a certain region of space, the electric field is along the z-direction throughout. The magnitude of the electric field is, however, not constant but increases uniformly along the positive z-direction, at the rate of $10^5$ NC$^{-1}$ per meter. What is the torque experienced by a system having a total dipole moment equal to $10^{-7}$ C-m in the negative z-direction?

The mass of a lift is $2000 \text{ kg}$. When the tension in the supporting cable is $28000 \text{ N}$, its acceleration is:

A truck is stationary and has a bob suspended by a light string in a frame attached to the truck. The truck suddenly moves to the right with an acceleration of $a$. In the frame of the truck, the pendulum will tilt:

Two equal positive charges $Q$ are fixed at points $(a, 0)$ and $(-a, 0)$ on the x-axis. An opposite charge $-q$ at rest is released from a point $(0, y)$ on the y-axis. The charge $-q$ will:

Given below are two statements: Statement I: In an AC circuit, the current through a capacitor leads the voltage across it. Statement II: In AC circuits containing pure capacitance only, the phase difference between the current and the voltage is $\pi$.

A block of mass $m$ is placed on a smooth inclined wedge ABC of inclination $\theta$ as shown in the figure. The wedge is given an acceleration '$a$' towards the right. The relation between $a$ and $\theta$ for the block to remain stationary on the wedge is:

A block $B$ is pushed momentarily along a horizontal surface with an initial velocity $v$. If $\mu$ is the coefficient of sliding friction between $B$ and the surface, the block $B$ will come to rest after a time:

A person of mass $60 \text{ kg}$ is inside a lift of mass $940 \text{ kg}$ and presses the button on control panel. The lift starts moving upwards with an acceleration $1.0 \text{ m/s}^2$. If $g=10 \text{ m/s}^2$, the tension in the supporting cable is:

For very high frequencies, the effective impedance of the circuit (shown in the figure) will be:

Three charges $+4q$, $Q$ and $q$ are placed in a straight line of length $l$ at points $0$, $l/2$ and $l$ distance away from one end respectively. What should be $Q$ in order to make the net force on $q$ to be zero?

In the figure given below, the position-time graph of a particle of mass 0.1 kg is shown. The impulse at t = 2 sec is: