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The impedance of a choke coil is $25\Omega$ and its reactance is $24\Omega$. The resistance of the choke coil is

Figure shows three temperature scales with the freezing and boiling point of water indicated. A change of ${25}^{\circ }P,{25}^{\circ }Q,{25}^{\circ }R$ are denoted by $X_1,X_2,X_3$ respectively. Which of the following is correct?

An air bubble in a glass slab with refractive index $1.5$ (near normal incidence) is $5\text{cm}$ deep when viewed from one surface and $3\text{cm}$ deep when viewed from the opposite face. The thickness (in $\text{cm}$) of the slab is

A stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. What is the tension in the string?
What is the maximum speed with which the stone can be whirled around if the string can withstand a maximum tension of 200 N?

Consider the reaction : $N_2+3H_2\to 2N{H}_3$ carried out at constant temperature and pressure. If $△H$ and $△U$ are the enthalpy and internal energy changes for the reaction, which of the following expressions is true?

1. 4

An AC circuit consists of an inductor of inductance $0.5\text{H}$ and a capacitor of capacitance $8\mu F$ in series. The current in the circuit is maximum, when the angular frequency of the source is -



Impedance for AC LC circuit is given by $Z=|X_L-X_C|$.

A positive charge with charge $q$ is moving with speed $v$ in the region of uniform magnetic field $B$ at the instant shown in figure. An external electric field is to be applied so that the charged particle follows a straight line path with the same uniform velocity. The magnitude and direction of electric field required are respectively

A
steel wire has a length of 12.0 m and a mass of 2.10 kg. What should
be the tension in the wire so that speed of a transverse wave on the
wire equals the speed of sound in dry air at 20 °C = 343 m s^–1.

The period of simple pendulum is measured as T in a stationary lift. If the lift moves upwards with an acceleration of 5 g, the period will be

A uniform horizontal rod of length $0.40\text{m}$ and mass $1.2\text{kg}$ is supported by two identical wires as shown in figure. Where a mass of $4.8\text{kg}$ should be placed from the left end of the rod, so that the same tuning fork may excite the wire on left into its fundamental vibrations and that on right into its first overtone? (Take $g=10{\text{m/s}}^2$)

All bulbs in the circuit shown in the figure are identical. Which bulb has maximum brightness .

A force of 25N acts on a body at rest for 0.2s and a force of 70N act for next 0.1s in opposite direction. If the final velocity of the body is 5m/s the mass of the body is?

A point moves with uniform acceleration and $V_1,V_2$ and $V_3$ denote the average velocities in the three successive intervals of time $t_1.t_2$ and $t_3$ Which of the following relations is correct

The threshold frequency for a certain photosensitive metal is ${\nu }_0$. When it is illuminated by light of frequency $\nu =2{\nu }_0$, the maximum velocity of photoelectrons is $v_0$. What will be the maximum velocity of the photoelectrons when the same metal is illuminated b a light of frequency $\nu =5{\nu }_0$?

The weight of an object at the center of a planet of radius R is:

A silver ball of radius $48\text{cm}$ is suspended by a thread in a vacuum chamber. Ultraviolet light of wavelength $200\text{nm}$ is incident on the ball for some time, during which a total light energy of $10\times {10}^{-7}\text{J}$ falls on the surface. Assuming that on the average for every ten thousand photons is able to eject a photoelectron, find the electric potential at the surface of the ball assuming zero potential at infinity.

A ball is swinging with the help of thread as shown in the figure. The component of $mg$ perpendicular to thread is

A source of sound with adjustable frequency produces $2$ beats per second with a tuning fork, when its frequency is either $466\text{Hz}$ or $470\text{Hz}$. What is the frequency of the tuning fork ?

If $\begin{array}{c}{\sin }^{-1}x+{\sin }^{-1}y=\frac{2\pi }{3},\end{array}$ then $\begin{array}{c}{\cos }^{-1}x+{\cos }^{-1}y=\end{array}$

A car starts from rest to cover a distance $s$. The coefficient of friction between the road and the tyres is $\mu$. The minimum time in which the car can cover the distance is proportional to

Two rotating bodies A and B of masses $m$ and $2m$ with moments of inertia $I_A$ and $I_B$ ($I_B$ > $I_A$) have equal kinetic energy of rotation. If $L_A$ and $L_B$ be their angular momenta respectively, then

A concave mirror of focal length $f$ produces an image $n$ times the size of the object. If the image is real, then the distance of the object from the mirror is

Calculate the $rms$ value of the $emf$ for a cycle, whose time variation is shown in figure.

A solid copper sphere (density $\rho$ and specific heat capacity (c) of radius r at an initial temperature 200K is suspended inside a chamber whose walls are at almost 0K. The time required (in $\mu$ s) for the temperature of the sphere to drop to 100 K is

A body is thrown with velocity $20m/s$ at an angle of ${60}^{\circ }$ with the horizontal. The time gap between the two positions of body where velocity of body makes an angle of ${30}^{\circ }$ with horizontal is

A football is kicked at an angle θ = ${45}^{\circ }$. It is intended that the ball lands in the back of a moving truck, which has a trunk of length L = 5 m. If the initial horizontal distance from the back of the truck to the ball, at the instant of the kick is 5 m & the truck moves directly away from the ball at velocity V = 9 m/s. What is approximate maximum & minimum velocity (in m/s) so that ball lands on the truck? (Assume the ball & back of the truck to be at the same horizontal level)

Ultraviolet light of wavelength $300\text{nm}$ and intensity $1{\text{W/m}}^2$ falls on the surface of a photosensitive material. If one percent of the incident photons produce photoelectrons, then the number of photoelectrons emitted per second from an area of $1{\text{cm}}^2$ of the surface is nearly

A block of $2\text{kg}$ is moving on a frictionless non-metal surface with a velocity of $1{\text{ms}}^{-1}$ towards another block of equal mass with a fixed spring is kept at rest as shown in figure. The Force constant of the spring is $100{\text{Nm}}^{-1}$. Find the maximum compression of the spring.

A short bar magnet placed in a horizontal plane has its axis aligned along the magnetic north-south direction. Null points are found on the axis of the magnet at $14\text{cm}$ from the centre of the magnet. The earth's magnetic field at the place is $0.36\text{G}$ and the angle of dip is zero. What is the total magnetic field on the normal bisector of the magnet at the same distance as the null-point $\left(\text{i.e.,}14\text{cm}\right)$ from the center of the magnet?

Find the $y-$ intercept of the line passing through the points $A(3,-2)$ and $B(-1,3)$.

A block of weight 50N is pulled along a rough horizontal surface . If coefficient of friction is 1 , then the least possible force that can move the block is..