Explore topic-wise InterviewSolutions in Current Affairs.

What is the minimum time required for $50Hz$. A.C to change its value from zero to rms value?

The energy that should be added to an electron to reduce its de Broglie wavelength from one nm to 0.5 nm is

The photoelectric work function for a metal surface is 4.125 eV. The cut-off wavelength for this surface is

The rate at which a particular decay process occurs in a radioactive sample, is proportional to the number of radioactive nuclei present. If N is the number of radioactive nuclei present at some instant, the rate of change of N is $\frac{dN}{dt}=-\lambda N$.

At $t=\infty$, which of the following incorrect?

Compressibility factor is the ratio of:

A radioactive nucleus of mass number 'A', initially at rest, emits an $\alpha$ - particle with a speed 'v'. What will be the recoil speed of the daughter nucleus?

Uncertainity in position of a minute particle of mass 25g in space is ${10}^{-5}$ m. What is the uncertainity in its velocity (in m$s^{-1}$) ? (h= 6.6 $\times$ ${10}^{-34}$ Js)

A particle executes linear simple harmonic motion with an amplitude of 2 cm. When the particle is at 1 cm from the mean position, the magnitude of its velocity is equal to that of its acceleration. Then its time period in seconds is:

The displacement x (in centimetres) of an oscillating particle varies with time t (in seconds) as
$x=2cos(0.5\pi t+\frac{\pi }{3})$
The magnitude of the maximum acceleration of the particle in $cm{s}^{-2}$ is

The dot product of mutually perpendicular vectors is always:

The resultant of $\overrightarrow{P}$ and $\overrightarrow{Q}$ is perpendicular to $\overrightarrow{P}$. What is the angle between $\overrightarrow{P}$ and $\overrightarrow{Q}$

If the internal resistance of a cell is 20 ohm and resistance of the circuit is also 20 ohm. Will the current remain same whether the given n identical cells are in series or in parallel?

A simple harmonic motion is represented by F(t) = 10 sin (20t + 0.5). The amplitude of the S.H.M. is

[DPMT 1998; CBSE PMT 2000; MH CET 2001]

Energy required to move a body of mass m from an orbit of radius 2R to 3R is

One body is dropped, while a second body is thrown downward with an initial velocity of $1{\text{m s}}^{-1}$ simultaneously. The separation between these is $18\text{m}$ after a time

The instantaneous displacement of a simple harmonic oscillator is given by y = A cos (ωt + n/4). Its speed will be maximum at the time:

Viscosity of gases _______with temperature, whereas viscosity of liquids _______with temperature.

A circular disc of radius R is free to rotate about an axis passing through its centre. An external tangential force F is applied on the disc along its edge. If the angular velocity of disc is increased from 0 to ωin a time t then the work done by F during same time t is

The equation of a progressive wave is given by $y=asin(628t-31.4x)$ If the distances are expressed in cms and time in seconds, then the wave velocity will be

[DPMT 1999]

A 2 m rod of mass 1 kg rotates at an angular speed of 15 rad/s about its ends. Then K.E. is

A ship of mass $3\times {10}^7$ kg initially at rest is pulled by a force of $5\times {10}^4$ N through a distance of 3 m. Assume that the resistance due to water is negligible, the speed of the ship is

A cannon ball is fired with a velocity 200 m/sec at an angle of ${60}^{\circ }$ with the horizontal. At the highest point of its flight it explodes into 3 equal fragments, one going vertically upwards with a velocity 100 m/sec, the second one falling vertically downwards with a velocity 100 m/sec. The third fragment will be moving with a velocity

A body is thrown horizontally from the top of a tower of height 5 m. It hits the ground at a distance of 10 m from the foot of the tower. The initial velocity of the body is (g = 10 m$s^{-2}$)

A traveling wave in a stretched string is described by the equation;

y = a sin (Kx - ωt).

The maximum particle velocity is:

The frequency of the incident light falling on a photosensitive metal plate is doubled, the kinetic energy of the emitted photoelectrons is

A girl walks 4 km towards west then, she walks 3 km in a direction ${30}^{\circ }$ east of north and stops. Determine the girl's displacement from her initial point of departure.

A racing car is travelling along a striaght track at a constant velocity of $40\text{m/s}$. A fixed TV camera is recording the event as shown in figure. In order to keep the car in view, the angular velocity of camera in the position shown should be

If $y=3t^2-4t$, then minima of $y$ will be at

Three equal charges, $2.0\times {10}^{-6}C$ Each are held fixed at the three corners of an equilateral triangle of side 5 cm. Find the coulomb forc eexperiencd by one of the charges due to the rest two

A particle is projected from the bottom of an inclined plane of angle ${30}^{\circ }$ with a velocity of $20\text{m/s}$ at an angle of ${45}^{\circ }$ with the horizontal. Find the horizontal distance travelled by the particle before it hits the plane.

Two electric bulbs A and B are rated as 60W and 100W. if they are connected in parallel to the same source, then

Block shown in column I is performing SHM with the amplitude ‘A’. Initial conditions have also been mentioned in diagrams accordingly. Answer the following questions relating these columns to each other.

Which of the option, is correct combination when block is at rest initially and have positive acceleration?

The distance between two point objects P and Q is 32 cm. A convex lens of focal length 15 cm is placed between them so that the images of both the objects are formed at the same place. The distance of P from the lens could be

Two blocks of masses 5 kg and 10 kg are connected by a massless spring. A force of 20 N acts on 10 kg mass as shown. At the instant, 5 kg mass has an acceleration of 0.4 $m{s}^{-2}$ the acceleration of 10 kg mass is

The pitch of a screw gauge is $1\text{mm}$ and there are $100$ divisions on circular scale. When the faces $A$ and $B$ are just touching each without putting anything between the studs, the ${32}^{\text{nd}}$ division of the circular scale coincides with the reference line. The error in measurement due to screw gauge will be (zero of linear scale is not hidden from circular scale when $A$ and $B$ touches)

When 1 centimeter thick surface is illuminated with light of wavelength $\lambda$, the stopping potential is V. When the same surface is illuminated by light of wavelength $2\lambda$, the stopping potential is $\frac{V}{3}$. Threshold wavelength for metallic surface is:

In the given figure, if each plate has area A and separation between plates is d, then equivalent capacitance between A & B is

In the arrangements shown in the figure below, block $A$ is connected to a spring and another block $B$ rests on $A$ and the system performs simple harmonic motion with a time period of $2\text{sec}$. The coefficient of static friction between $A$ and $B$ is $0.6$. The maximum amplitude of oscillation which the system can have, so that there is no relative motion between $A$ and $B$ is:
[Take $g=10{\text{m/s}}^2\&{\pi }^2\approx 10$]

A musical instrument is made using four different metal strings. $1,2,3$ and 4 with mass per unit length $\mu ,2\mu ,3\mu$ and $4\mu$ respectively. The instrument is played by vibrating the strings by varying the free length in between the range $L_0\text{and}2L_0\text{. It is found that in string-}1\text{(}\mu )$ at free length $L_0$ and tension $T_0$ the fundamental mode frequency is $f_0.$ List-I gives the above four strings while List-II lists the magnitude of some quantity.

If the tension in each string is $T_0$, the correct match for the highest fundamental frequency in $f_0$ units will be,

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 body starts from rest and is accelerated by a force $F=kt\left(\text{N}\right)$. Options given below show the variation of power with time. Find the correct option related to the above case.

A 6-volt battery of negligible internal resistance is connected across a uniform wire AB of length 100 cm. The positive terminal of another battery of emf 4 V and internal resistance 1 $\Omega$ is joined to the point A as shown in figure (32-E28). Take the potential at B to be zero. (a) What are the potentials at the points A and C ? (b) At which point D of the wire AB, the potential is equal to the potential at C ? (c) If the points C and D are connected by a wire, what, will be the current through it ? (d) If the 4 V battery is replaced by 7.5 V battery, what would be the answers of parts (a) and (b) ?

figure (32-E28)