Explore topic-wise InterviewSolutions in Current Affairs.

An elevator accelerates upwards at a constant rate. A uniform string of length $L$ and mass $m$ supports a small block of mass $M$ that hangs from the ceiling of the elevator. The tension at distance $l$ from the ceiling is $T$. The acceleration of the elevator is

Energy levels A,B,C of an atom are shown below


If $E_A<E_B<E_C$, the wavelength emitted due to transistion from C to A is ${\lambda }_3$then correct statements of the following is

Figure illustrates a cycle conducted with $n$ moles of an ideal gas. In the states $a$ and $b$ the gas temperature are $T_a$ and $T_b$ respectively. Temperature of the gas in the state $\text{c}$ is

In two arms of a U tube one of them are maintained in mercury and other is in water. Consider two points on each arm at same height, will the pressure of them become same. If yes , does'nt it matter the density of fluids.

A circuit containing a
80 mH inductor and a 60 μF
capacitor in series is connected to a 230 V, 50 Hz supply. The
resistance of the circuit is negligible.

(a) Obtain the
current amplitude and rms values.

(b) Obtain the
rms values of potential drops across each element.

(c) What is the
average power transferred to the inductor?

(d) What is the
average power transferred to the capacitor?

(e) What is the total average power absorbed by the circuit?
[‘Average’ implies ‘averaged over one cycle’.]

A wooden block, with a coin placed on its top, floats in water as shown in fig. the distance l and h are shown there. After some time the coin falls into the water. Then

A rod is released from the position as shown in figure. If there is sufficient friction between the rod and the plane to prevent slipping, the minimum value of friction co-efficient between rod and ground is

On a cold winter day, the atmospheric temperature is -$\theta$ (on Celsius scale) which is below 0${}^{\circ }$C. A cylindrical drum of height h made of a bad conductor is completely filled with water at 0 ${}^{\circ }$ C and is kept outside without any lid. Calculate the time taken for the whole mass of water to freeze. Thermal conductivity of ice is K, $\rho$ is the density and latent heat of fusion is L. Neglect expansion of water on freezing

A short electric dipole has dipole moment of $3\sqrt{2}\times {10}^{-10}\text{C m}$. The electric potential due to the dipole at a point which is at a distance $0.3\text{m}$ from the centre of the dipole, situated on a line making an angle of ${45}^{\circ }$ with the dipole axis is $(\frac{1}{4\pi {ϵ}_0}=9\times {10}^9{\text{N m}}^2/{\text{C}}^2)$ :

A particle returns to the starting point after $10\text{s}$. if the rate of change of velocity during the motion is constant, then its location after $7\text{s}$ will be same as that after

For a normal eye, the least distance of distinct vision is

[CPMT 1984]

1. 216

A plane electromagnetic wave propagating in the $x-$direction in vacuum has wavelength of $6.0\text{mm}$. The electric field is in the $y-$direction and its maximum magnitude is $33{\text{Vm}}^{-1}$.



$\left(iii\right)$ Find the average energy density of the electromagnetic wave.



​​​​​​​$[$1 Mark$]$

A wooden block of mass $10g$ is dropped from rest from the top of a cliff $100m$ high. Simultaneously, a bullet of mass $10g$ is fired from the foot of the cliffupward with a velocity of $100m{s}^{-1}$. After what time, will the bullet and the block meet?

An electron is projected horizontally with a kinetic energy of 10 keV. A magnetic field of strength $1.0\times {10}^{-7}$ T exists in the vertically upward direction. (a) Will the electron deflect towards right or towards left of its motion ? (b) Calculate the sideways deflection of the electron in travelling through 1 m. Make appropriate approximations.

Two spherical balls of mass 10 kg each are placed 10 cm apart. Find the gravitional force of attraction between them.

Find the displacement amplitude of particles of air of density $1.5{\text{kg/m}}^3$ if the intensity and frequency of sound are $8\times {10}^{-6}{\text{W/m}}^2$ and $5000\text{Hz}$ respectively.

[speed of sound in air $=330\text{m/s}$]

Two conductors of irregular shapes placed near each other are connected to the two terminals of a battery of $50\text{V}$. It is observed that the charge on one of the conductors is $2\mu \text{C}$. The capacitance of this arrangement is

A satellite moves around the earth in a circular orbit of radius $r$ with speed $v$. If the mass of the satellite is $M$, its total energy is

In the situation shown in the figure, block of mass $m$ is pulled so that the spring is elongated without the block slipping. Which of the following graphs correctly represents the relation between static frictional force and elongation for angle of inclination ${37}^{\circ }$ and ${53}^{\circ }$. The spring constant is $k$ and the coefficient of friction is ${\mu }_s=0.8$.

Average speed of traffic advancement is $5m/s$ when green and red lights remain open for same duration. To avoid traffic jams at peak hours, duration of opening green light is doubled keeping red duration same. What is new speed of traffic advancement in $m/s$ is

Two identical metal balls with charges +2Q and -Q are separated by the same distance, and exert a force F on each other. They are joined by a conducting wire, which is then removed. The magnitude of the force between them will now be

Light is incident normally on face $AB$ of a prism as shown in figure. A liquid of refractive index $\mu$ is placed on face $AC$ of the prism. The prism is made of glass of refrctive index $3/2$. The limits of $\mu$ for which total internal reflection takes place on face $AC$ is

The extension in a uniform rod of length $l$, mass $m$, cross sectional area $A$ and young's modulus $Y$ when it is suspended vertically at one end is

In the figure, the intensity of waves arriving at D from two coherent sources $s_1$ and $s_2$ is $I_0$. The wavelength of the wave is $\lambda =4m$. Resultant intensity at D will be

The length of the wire between the pulleys is $1.5\text{m}$ and its mass is $12\text{gm}$. Find the frequency of vibration, with which the wire vibrates in two loops leaving the middle point of the wire between the pulleys at rest.

Use value of $\sqrt{11250}\approx 106$

A string breaks if its tension exceeds 10 newtons. A stone of mass 250 gm tied to this string of length 10 cm is rotated in a horizontal circle. The maximum angular velocity of rotation can be

A stone projected with a velocity $u$ at an angle $\theta$ with the horizontal reaches maximum height $H_1$. When it is projected with velocity $u$ at an angle $(\frac{\pi }{2}-\theta )$ with the horizontal, it reaches the maximum height $H_2$. The relation between the horizontal range $R$ of the projectile, $H_1$ and $H_2$ is

A fly flies from a point $P(0,2,5)$ to the point $Q(3,1,6)$. The magnitude of displacement covered by it is

A vehicle uniformly covers 10 km in 10 min, and then again uniformly covers the next 15 km in 6 min. Which of the following graphs correctly depicts the motion of the vehicle?

Line AB denotes the motion for the first 10 km, and line BC represents the motion for the next 15 km.

A simple microscope is rated $\text{5X}$ for a normal and relaxed eye. What will be its magnifying power for a relaxed eye, whose near point is $50\text{cm}$?

One of the lines in the emission spectrum of ${\text{Li}}^{2+}$ has the same wavelength as that of $2^{nd}$ line of Balmer series in hydrogen spectrum. The electronic transition corresponding to this line is :-