Explore topic-wise InterviewSolutions in .

Consider the situation shown in figure (38-E18). The wire PQ has a negligible resistance and is made to slide on the three rails with a constant speed of $5cm{s}^{-1}$. Find the current in the $10\Omega$ resistor when the switch S is thrown to (a) the middle rail (b) the bottom rail.

A particle of mass $m$ begins to slide down a fixed smooth sphere from the top as shown. What is its acceleration when it breaks off the sphere?

If the magnitude of the vector product of two vectors is negative, then the angle between them has the range

A bird is flying up at angle ${\sin }^{-1}\left(\frac{3}{5}\right)$ with the horizontal. A fish in a pond looks at that bird when it is vertically above the fish. The angle at which the bird appears to fly (to be fish)is $({\mu }_{\omega }=\frac{4}{3})$

Two particles $A$ and $B$ are moving on two concentric circles of radii $R_1$ and $R_2$ respectively with equal angular speed $\omega \text{rad/s}$. At $t=0$, their positions and linear velocities are shown in the figure. Then relative velocity $(\text{m/s}$) of $A$ with respect to $B$ (i.e $\overrightarrow{v_{AB}})$ at $t=\frac{\pi }{2\omega }\text{s}$ is given by:

A particle of mass $5\text{kg}$ is projected vertically upwards from point $D$ on the ground. The ratio of potential energy at point $B$ and at point $A$ is (take point D as reference)

The position of a particle is given by $\overrightarrow{r}=3t\hat{i}+\sqrt{3}{t}^2\hat{j}-4\hat{k}$, where $t$ is in seconds and $\overrightarrow{r}$ is in meters. Find out magnitude and direction of velocity $\overrightarrow{v}$ with horizontal at $t=\sqrt{3}\text{s}$.

A radiation of energy=E falls normally on a perfectly reflecting surface.The momentum transferred to the surface is (C=Velocity of light):

What is the magnetic field $\overrightarrow{dB}$ at a distance $\overrightarrow{r}$ due to a small current element $\overrightarrow{dl}$ carrying current I?

A student has three concave mirrors A B and C of focal lengths 20cm, 15cm and 10cm respectively. For each concave mirror, he performs the experiment of image formation for three values of an object distance of 30cm, 10cm and 20cm. Give reason and answer the following:
1. For the three object distances identify the mirror which will form an image equal in size to that of the object. Find at least one value of object distance.
2. Out of the three mirrors identify the mirror which would be used for shaving purpose.

1. 4

A block of mass m is kept on a horizontal ruler. The friction coefficient between the ruler and the block is $\mu .$ the ruler is fixed at one end and the block is at a distance L from the fixed end. The ruler is rotated about the fixed end in the horizontal plane through the fixed end. (a) What can the maximum angular speed be for which the block does not slip ? (b) If the angular speed of the ruler is uniformly increased from zero at an angular acceleration $\alpha ,$ at what angular speed will the block slip ?

A disc of mass $M$ radius $R$ is fixed about an axis as shown in figure. If a particle of mass $\frac{M}{4}$ moving with speed $v$ perpendicular to the disc plane, hits the disc at point $P$ and sticks to the disc, the disc starts rotating about its axis as shown. Find the angular velocity of the system (disc + particle) after the hit.

The work functions for sodium and copper are 2eV and 4eV. Which of them is suitable for a photocell with $4000\stackrel{\circ }{A}$ light

If $x=at+b{t}^2$, where $x$ is the distance travelled by the body in $\text{km}$ and $t$ is the time taken by it in $\text{s}$, then the unit of $b$ will be

X-rays are incident normally on a crystal of lattice constant 0.6 nm. The first order reflection of diffraction from the crystal occurs at an angle of ${30}^{\circ }$. What is the wavelength of X-rays used?

Backlash error is present in

Moment of inertia of solid hemisphere of mass M and radius R about an axis passing through centre of mass as shown, is

A parallel plate capacitor of capacitance $200\text{pF}$ having area $100{\text{cm}}^2$ is completely filled with a dielectric material of dielectric constant $k=2.8$ at $20\text{V}$ potential difference, find the magnitude of electric field in the dielectric.

In a meter bridge experiment, null point is obtained at $20\text{cm}$ from one end of the wire when resistance $x$ is balanced against resistance $y$. If $x<y$, then where will be the new position of the null point from the same end, if one decides to balance a resistance of $4x$ against $y$ ?

Two slabs A and B of different materials but of the same thickness are joined as shown in the figure. The thermal conductivities of A and B are $k_1$ and $k_2$ respectively. The thermal conductivity of the composite slab will be

The potential at the centre of the base of a solid hemisphere of mass $m$ and radius $R$ is

The maximum height reached by the projectile is $4m$. The horizontal range is $12m$. Velocity of projection (in $m{s}^{-1}$) is
($g$ is acceleration due to gravity)

One $\text{mole}$ of an ideal monoatomic gas is taken at a temperature of $300\text{K}$. If the volume is doubled keeping its pressure constant, change in internal energy is

Water is flowing through a horizontal tube of non-uniform cross section. At a place, the radius of the tube is $2\text{cm}$ and velocity is $6\text{m/s}$. What will be the velocity of water where the radius of pipe is $4\text{cm}$?

Two identical blocks P and Q have mass ‘m’ each. They are attached to two identical springs initially unstretched. Now the left spring (along with P) is compressed by $\frac{A}{2}$ and the right spring (along with Q) is compressed by A. Both the blocks are released simultaneously. They collide perfectly inelastically. Initial time period of both the blocks was T. [consider k as spring constant of each spring]

The time period and amplitude of oscillation of the combined mass is respectively,

The simple pendulum of mass $2\text{kg}$ is released from rest in the horizontal position. As it reaches the bottom position, the cord wraps around the smooth fixed pin at $B$ and continues on the smaller arc in the vertical plane. Calculate the magnitude of the force $R$ supported by the pin at $B$ when the pendulum passes the position $E$.

[Take $g=9.8{\text{m/s}}^2$]

Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string and are then placed on a frictionless surface as shown in the figure. The system is pulled by a force F = 10 N,, then tension $T_1=$