Recent questions tagged set a

Two long current thin wires, both with current I, are held by insulating threads of length L and are in equilibrium as shown in the fig, with threads making an angle $\theta$ with the vertical . If wires have mass $\lambda$ per unit length then the value of I is :

asked Oct 12, 2015 by meena.p

1 answer

Two coaxial solenoids of different radii carry current I in the same direction. Let $\overrightarrow{F_1}$ be the magnetic force on the inner solenoid due to the outer one and $\overrightarrow{F_2}$ be the magnetic force on the outer solenoid due to the inner one . Then :

asked Oct 12, 2015 by meena.p

1 answer

In the circuit shown, the current ion the $1 \Omega$ resistor is :

asked Oct 12, 2015 by meena.p

1 answer

When $5V$ potential difference is applied across a wire of length $0.1\;m$, the drift speed of electrons density in the wire is $8 \times 10^{28}\;m^{-3}$, the resistivity of the material is close to :

asked Oct 12, 2015 by meena.p

1 answer

In the given circuit , charge $Q_2$ on the $2 \mu F$ capacitor changes as C is varied from $1 \mu F$ to $3 \mu F$ . $Q_2$ as function of 'C' is given properly by :

asked Oct 12, 2015 by meena.p

1 answer

A uniformly charged solid sphere of radius R has potential $V_0$ (measured with respect to $\infty$) on its surface. For this sphere the equipotential surfaces with potentials $\large\frac{3V_0}{2},\frac{5V_0}{4},\frac{3V_0}{4}$ and $\large\frac{V_0}{4}$ have radius $R_1, R_2, R_3$ and $R_4$ respectively . Then

asked Oct 12, 2015 by meena.p

2 answers

A long cylindrical shell carries positive surface charge $\sigma$ in the upper half and negative surface $- \sigma$ in the lower half. The electric field lines around the cylinder will look figure given in :

asked Oct 12, 2015 by meena.p

1 answer

A train is moving on a straight track with speed $20ms^{-1}$. It is blowing its Whistle at the frequency of 1000 Hz. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound =$320\;ms^{-1})$ close to :

asked Oct 12, 2015 by meena.p

1 answer

For a simple pendulum, a graph is plotted between its kinetic energy (KE) and potential energy (PE) against its displacement d. Which one of the following represents these correctly?

asked Oct 12, 2015 by meena.p

1 answer

Consider an ideal gas confined in an isolated closed chamber. As the gas undergoes an adiabatic expansion , the average time of collision between molecules increases as $V^q$, where V is the volume of the gas. The value of q is : $\bigg[\gamma =\large\frac{C_p}{C_v}\bigg]$

asked Oct 12, 2015 by meena.p

1 answer

A solid body of constant heat capacity $1 L/^{\circ}C$ is being heated by keeping it in contact with reservoirs in two ways : (i) Sequentially keeping in contact with 2 reservoirs such that each reservoir supplies same amount of heat . (ii) Sequentially keeping in contact with 8 reservoirs such that each reservoir supplies same amount of heat . In both the cases body is brought from initial temperature $100^{\circ}$ to final temperaure $200 ^{\circ}$ Entropy change of the body in the two cases respectively is :

asked Oct 12, 2015 by meena.p

1 answer

Consider a spherical shell of radius R at temperature T. The black body radiation inside it can be considered as an ideal gas of photons with internal energy per unit volume $u= \large\frac{U}{V}$$ \infty T^4$ and pressure $p= \large\frac{1}{3}\bigg( \frac{U}{V}\bigg)$. If the shell now undergoes an adiabatic expansion the relation between T and R is :

asked Oct 8, 2015 by meena.p

1 answer

A pendulum made of a uniform wire of cross sectional area A has time period T.When an addition mass M is added to its bob, the time period change to $T_M$. If the young's modulus of material of the wire is Y then $\large\frac{1}{Y}$ is equal to:

asked Oct 8, 2015 by meena.p

1 answer

From a solid sphere of mass M and radius R, a spherical portion of radius $\large\frac{R}{2}$ is removed , as shown in fig. Taking gravitational potential $V=0$ at $ r= \infty$ , the potential at the center of the cavity thus formed is

asked Oct 8, 2015 by meena.p

1 answer

From a solid sphere of mass M and radius R a cube of maximum possible volume is cut. Moment of inertia of cube about an axis passing through its center and perpendicular to one of its faces is :

asked Oct 8, 2015 by meena.p

1 answer

Distance of the center of mass of a solid uniform cone from its vertex is $z_0$ . If the radius of its base is R and its height is h then $ z_0$ is equal to :

asked Oct 8, 2015 by meena.p

1 answer

A particle of mass m moving in the x direction with speed 2v is hit by another particle of mass 2m moving in the y direction with speed v. If the collision is perfectly inelastic , the percentage loss in the energy during the collision is close to :

asked Oct 8, 2015 by meena.p

1 answer

Given in the figure are two blocks A and B of weight 20 N and 100 N , respectively . These are being pressed against a wall by a force as shown in fig. If the coefficient of friction between the blocks is $0.1$ and between block B and the wall is $0.15$ , the frictional force applied by the wall on block B is

asked Oct 8, 2015 by meena.p

1 answer

The period of oscillation of a simple pendulum is $ T= 2 \pi \sqrt {\large\frac{L}{g}}$ Measured value of L is $20.0\;cm$ known to 1mm accuracy and time for 100 oscillation of the pendulum is found to be 90 s using a wrist watch of 1s resolution. The accuracy in the determination of g is :

asked Oct 8, 2015 by meena.p

1 answer

Two stones are thrown up simultaneously from the edge of a cliff $240\;m$ high with initial speed of $10 m/s$ and $40 m/s$ respectively. Which of the following graph best represents the time variation of relative position of the second stone with respect to the first ? (Assume stones do not rebound after hitting the ground and neglect air resistance , take $g= 10 m/s^2$) (The figures are schematic and not drawn to scale )

asked Oct 8, 2015 by meena.p

1 answer

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