In the circuit show below, the key K is closed at t=0. T
Question: In the circuit show below, the key $\mathrm{K}$ is closed at $\mathrm{t}=0$. The current through the battery is : $\frac{V\left(R_{1}+R_{2}\right)}{R_{1} R_{2}}$ at $t=0$ and $\frac{V}{R_{2}}$ at $t=\infty$$\frac{\mathrm{VR}_{1} \mathrm{R}_{2}}{\sqrt{\mathrm{R}_{1}^{2}+\mathrm{R}_{2}^{2}}}$ at $\mathrm{t}=0$ and $\frac{\mathrm{V}}{\mathrm{R}_{2}}$ at $\mathrm{t}=\infty$$\frac{\mathrm{V}}{\mathrm{R}_{2}}$ at $\mathrm{t}=0$ and $\frac{\mathrm{V}\left(\mathrm{R}_{1}+\mathrm{R}_{2}\right)}...
Read More →A pulley of radius
Question: A pulley of radius $2 \mathrm{~m}$ is rotated about its axis by a force $\mathrm{F}=\left(20 \mathrm{t}-5 \mathrm{t}^{2}\right)$ newton (where $\mathrm{t}$ is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotationis 10 $\mathrm{kg} \mathrm{m} \mathrm{m}^{2}$, the number of rotations made by the pulley before its direction of motion if reversed, is :-more than 6 but less than 9more than 9less than 3more than 3 but less than 6Correct ...
Read More →A small particle of mass
Question: A small particle of mass $\mathrm{m}$ is projected at an angle $\theta$ with the $\mathrm{x}$-axis with an initial velocity $\mathrm{v}_{0}$ in the $x-y$ plane as shown in the figure. At a time $t\frac{v_{0} \sin \theta}{g}$, the angular momentum of the particle is: Where $\hat{i}, \hat{j}$ and $\hat{k}$ are unit vectors along $x, y$ and $z$-axis respectively. $\frac{1}{2} m g v_{0} t^{2} \cos \theta \hat{i}$$-m g v_{0} t^{2} \cos \theta \hat{j}$$m g v_{0} t \cos \theta \hat{k}$$-\frac...
Read More →An inductor of inductance L=400mH and resistors of resistances
Question: An inductor of inductance $\mathrm{L}=400 \mathrm{mH}$ and resistors of resistances $\mathrm{R}_{1}=2 \Omega$ and $\mathrm{R}_{2}=2 \Omega$ are connected to a battery of emf $12 \mathrm{~V}$ as shown in the figure. The internal resistance of the battery is negligible. The switch $\mathrm{S}$ is closed at $\mathrm{t}=0$. The potential drop across $\mathrm{L}$ as a function of time is:- $6\left(1-\mathrm{e}^{-t / 0.2}\right) \mathrm{V}$$12 \mathrm{e}^{-5 \mathrm{t}} \mathrm{V}$$6 e^{-5 t...
Read More →Solve this following
Question: Directions : Question number 1, 2 and 3 are based on the following paragraph. Two moles of helium gas are taken over the cycle ABCDA, as shown in the $\mathrm{P}-\mathrm{T}$ diagram. The net work done on the gas in the cycle ABCDA is :- $1076 \mathrm{R}$$1904 \mathrm{R}$Zero$276 \mathrm{R}$Correct Option: , 4 Solution:...
Read More →A thin uniform rod of length
Question: A thin uniform rod of length $l$ and mass $m$ is swinging freely about a horizontal axis passing through its end. Its maximum angular speed is $\omega$. Its centre of mass rises to a maximum height of:$\frac{1}{2} \frac{l^{2} \omega^{2}}{g}$$\frac{1}{6} \frac{l^{2} \omega^{2}}{g}$$\frac{1}{3} \frac{l^{2} \omega^{2}}{\mathrm{~g}}$$\frac{1}{6} \frac{l \omega}{g}$Correct Option: , 2 Solution:...
Read More →Radiation of wavelength $lambda$, is incident on a photocell.
Question: Radiation of wavelength $\lambda$, is incident on a photocell. The fastest emitted electron has speed $\mathrm{v}$. If the wavelength of changed to $\frac{3 \lambda}{4}$, the speed of the fastest emitted electron will be :-$=v\left(\frac{3}{5}\right)^{1 / 2}$$v\left(\frac{4}{3}\right)^{1 / 2}$$v\left(\frac{4}{3}\right)^{1 / 2}$$=v\left(\frac{4}{3}\right)^{1 / 2}$Correct Option: , 2 Solution:...
Read More →Solve this following
Question: Directions : Question number 1,2 and 3 are based on the following paragraph. Two moles of helium gas are taken over the cycle $\mathrm{ABCDA}$, as shown in the $\mathrm{P}-\mathrm{T}$ diagram. The work done on the gas in taking it from $\mathrm{D}$ to $\mathrm{A}$ is :-$-690 \mathrm{R}$$+690 \mathrm{R}$$-414 R$$+414 \mathrm{R}$Correct Option: , 4 Solution:...
Read More →The anode voltage of photocell is kept fixed.
Question: The anode voltage of photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows : Correct Option: , 4 Solution: For constant intensity as wavelength decreases energy of photons increases and number of photons decreases. So it may seem that current should decrease. But the probability that a photon will be successful in emitting an electron will also increase. So as wavelength decreas...
Read More →Arrange the following electromagnetic radiations per quantum in
Question: Arrange the following electromagnetic radiations per quantum in the order of increasing energy :- A : Blue light B : Yellow light C : Xray D : RadiowaveB, A, D, CD, B, A, CA, B, D, CC, A, B, DCorrect Option: , 2 Solution:...
Read More →A red LED emits light at 0.1 watt uniformly around it.
Question: A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is :-5.48 V/m7.75 V/m1.73 V/m2.45 V/mCorrect Option: , 4 Solution:...
Read More →A projectile is given an initial velocity
Question: A projectile is given an initial velocity of $(\hat{\mathrm{i}}+2 \hat{\mathrm{j}}) \mathrm{m} / \mathrm{s}$, where $\hat{\mathrm{i}}$ is along the ground and $\hat{\mathrm{j}}$ is along the vertical. If $g=10 \mathrm{~m} / \mathrm{s}^{2}$, the equation of its trajectory is :$y=x-5 x^{2}$$y=2 x-5 x^{2}$$4 \mathrm{y}=2 \mathrm{x}-5 \mathrm{x}^{2}$$4 \mathrm{y}=2 \mathrm{x}-25 \mathrm{x}^{2}$Correct Option: , 2 Solution:...
Read More →A red LED emits light at 0.1 watt uniformly around it.
Question: A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is :-5.48 V/m7.75 V/m1.73 V/m2.45 V/mCorrect Option: Solution:...
Read More →his question has Statememtn-1 and Statement-2. Of the four choices given after the statements,
Question: This question has Statememtn-1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements. Statement-1 : A metallic surface is irradiated by a monochromatic light of frequency $vv_{0}$ (the threshold frequency). The maximum kinetic energy and the stopping potential are $K_{\max }$ and $V_{0}$ respectively. If the frequency incident on the surface is doubled, both the $\mathrm{K}_{\max }$ and $\mathrm{V}_{0}$ are also doubled. ...
Read More →Solve this following
Question: Directions : Question number 1,2 and 3 are based on the following paragraph. Two moles of helium gas are taken over the cycle ABCDA, as shown in the $\mathrm{P}-\mathrm{T}$ diagram. Assuming the gas to be ideal the work done on the gas in taking it from A to B is :- $400 \mathrm{R}$$500 \mathrm{R}$$200 \mathrm{R}$300Correct Option: 1 Solution:...
Read More →A water fountain on the ground
Question: A water fountain on the ground sprinkles water all around it. If the speed of water coming out of the fountain is $\mathrm{v}$, the total area around the fountain that gets wet is :-$\frac{\pi}{2} \frac{v^{4}}{g^{2}}$$\pi \frac{\mathrm{v}^{2}}{\mathrm{~g}^{2}}$$\pi \frac{v^{2}}{g}$$\pi \frac{\mathrm{v}^{4}}{\mathrm{~g}^{2}}$Correct Option: , 4 Solution:...
Read More →During the propagation of electromagnetic waves in a medium :
Question: During the propagation of electromagnetic waves in a medium :Electric energy density is equal to the magnetic energy densityBoth electric magnetic energy densities are zeroElectric energy density is double of the magnetic energy densityElectric energy density is half of the magnetic energy density.Correct Option: 1 Solution: Factual question...
Read More →Statement-1 : When ultraviolet light is incident on a photocell, its stopping potential is
Question: Statement-1 : When ultraviolet light is incident on a photocell, its stopping potential is $\mathrm{V}_{0}$ and the maximum kinetic energy of the photoelectrons is $\mathrm{K}_{\max }$. When the ultraviolet light is replaced by $\mathrm{X}$-rays, both $\mathrm{V}_{0}$ and $\mathrm{K}_{\max }$ increase. Statement-2 : Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light.Statement $-1$ is true, Statem...
Read More →Match List-I (Electromagnetic wave type) with List-II
Question: Match List-I (Electromagnetic wave type) with List-II (Its association/application) and select the correct option from the choices given below the lists: Correct Option: Solution: Factual Question...
Read More →A particle is moving
Question: A particle is moving with velocity $\vec{v}=K(y \hat{i}+x \hat{j})$, where $K$ is a constant. The general equation for its path is :$\mathrm{y}^{2}=\mathrm{x}^{2}+$ constant$y=x^{2}+$ constant$\mathrm{y}^{2}=\mathrm{x}+\mathrm{constant}$$x y=$ constantCorrect Option: 1 Solution:...
Read More →Solve this following
Question: Let $\overrightarrow{\mathrm{A}}=(\hat{\mathrm{i}}+\hat{\mathrm{j}})$ and $\overrightarrow{\mathrm{B}}=(2 \hat{\mathrm{i}}-\hat{\mathrm{j}})$. The magnitude of a coplanar vector $\overrightarrow{\mathrm{C}}$ such that $\overrightarrow{\mathrm{A}} \cdot \overrightarrow{\mathrm{C}}=\overrightarrow{\mathrm{B}} \cdot \overrightarrow{\mathrm{C}}=\overrightarrow{\mathrm{A}} \cdot \overrightarrow{\mathrm{B}}$, is given by :-$\sqrt{\frac{20}{9}}$$\sqrt{\frac{5}{9}}$$\sqrt{\frac{9}{12}}$$\sqrt{...
Read More →A particle has an initial
Question: A particle has an initial velocity of $3 \hat{\mathrm{i}}+4 \hat{\mathrm{j}}$ and an acceleration of $0.4 \hat{\mathrm{i}}+0.3 \hat{\mathrm{j}}$.7 units$8.5$ units10 units$7 \sqrt{2}$ unitsCorrect Option: , 4 Solution:...
Read More →The surface of a metal is illuminated with the light of
Question: The surface of a metal is illuminated with the light of $400 \mathrm{~nm}$. The kinetic energy of the ejected photoelectrons was found to be $1.68 \mathrm{eV}$. The work function of the metal is : (hc $=1240 \mathrm{eV}-\mathrm{nm})$$1.51 \mathrm{eV}$$1.68 \mathrm{eV}$$3.09 \mathrm{eV}$$1.41 \mathrm{eV}$Correct Option: , 4 Solution:...
Read More →An electromagnetic wave in vacuum has the electric and magnetic fields
Question: An electromagnetic wave in vacuum has the electric and magnetic fields $\overrightarrow{\mathrm{E}}$ and $\overrightarrow{\mathrm{B}}$, which are always perpendicular to each other. The direction of polarization is given by $\overrightarrow{\mathrm{X}}$ and that ofwave propagation by $\vec{k}$. Then$\overrightarrow{\mathrm{X}} \| \overrightarrow{\mathrm{B}}$ and $\overrightarrow{\mathrm{k}} \| \overrightarrow{\mathrm{E}} \times \overrightarrow{\mathrm{B}}$$\overrightarrow{\mathrm{X}} \...
Read More →If a source of power 4 kW produces
Question: If a source of power $4 \mathrm{~kW}$ produces $10^{20}$ photons/second, the radiation belongs to a part of the spectrum calledmicrowavesy-raysX-rays ultraviolet raysCorrect Option: , 3 Solution:...
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