In a Young's double slit experiment, slits are separated by
Question: In a Young's double slit experiment, slits are separated by $0.5 \mathrm{~mm}$, and the screen is placed $150 \mathrm{~cm}$ away. A beam of light consisting of two wavelengths, $650 \mathrm{~nm}$ and $520 \mathrm{~nm}$, is used to obtain interference fringes on the screen. The least distance from the common central maximum to the point where the bright fringes due to both the wavelengths coincide is :-$9.75 \mathrm{~mm}$$15.6 \mathrm{~mm}$$1.56 \mathrm{~mm}$$7.8 \mathrm{~mm}$Correct Op...
Read More →A current I flows in an infinity long wire with cross section
Question: A current I flows in an infinity long wire with cross section in the from of a semicircular ring of radius $R$. the magnitude of the magnetic induction along its axis is :-$\frac{\mu_{0} I}{2 \pi R}$$\frac{\mu_{0} I}{4 \pi R}$$\frac{\mu_{0} I}{\pi^{2} R}$$\frac{\mu_{0} I}{2 \pi^{2} R}$Correct Option: , 3 Solution:...
Read More →The temperature of an open
Question: The temperature of an open room of volume $30 \mathrm{~m}^{3}$ increases from $17^{\circ} \mathrm{C}$ to $27^{\circ} \mathrm{C}$ due to sunshine. The atmospheric pressure in the room remains $1 \times 10^{5} \mathrm{~Pa}$. If $\mathrm{n}_{\mathrm{i}}$ and $\mathrm{n}_{\mathrm{f}}$ are the number of molecules in the room before and after heating, then $n_{f}-n_{i}$ will be :-$2.5 \times 10^{25}$$-2.5 \times 10^{25}$$-1.61 \times 10^{23}$$1.38 \times 10^{23}$Correct Option: , 2 Solution:...
Read More →The box of a pin hole camera, of length
Question: The box of a pin hole camera, of length $\mathrm{L}$, has a hole of radius a. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength $\lambda$ the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size $\left(\right.$ say $b_{\min }$ ) when :-$a=\frac{\lambda^{2}}{L}$ and $b_{\min }=\sqrt{4 \lambda L}$$a=\frac{\lambda^{2}}{L}$ an...
Read More →Consider an ideal gas confined
Question: Consider an ideal gas confined in an isolated closed chamber. As the gas undergoes an adiabatic expansion, the average time of collision between molecules increases as $\mathrm{Vq}$, where $\mathrm{V}$ is the volume of the gas. The value of $q$ is :- $\left(\gamma=\frac{C_{p}}{C_{v}}\right)$$\frac{\gamma+1}{2}$$\frac{\gamma-1}{2}$$\frac{3 \gamma+5}{6}$$\frac{3 \gamma-5}{6}$Correct Option: 1 Solution:...
Read More →On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground.
Question: On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally, the Huygens' principle leads us to conclude that as it travels, the light beam :bends downwards bends upwards becomes narrower goes horizontally without any deflectionCorrect Option: , 2 Solution:...
Read More →An open glass tube is immersed
Question: An open glass tube is immersed in mercury in such a way that a length of $8 \mathrm{~cm}$ extends above the mercury level. The open of the tube is then closed and sealed and the tube is raised vertically up by addition $46 \mathrm{~cm}$. What will be length of the air column above mercury in the tube now ? (Atmospheric pressure $=76 \mathrm{~cm}$ of $\mathrm{Hg}$ )$38 \mathrm{~cm}$$6 \mathrm{~cm}$$16 \mathrm{~cm}$$22 \mathrm{~cm}$Correct Option: , 3 Solution:...
Read More →An electric charge
Question: An electric charge $+\mathrm{q}$ moves with velocity $\overrightarrow{\mathrm{V}}=3 \hat{\mathrm{i}}+4 \hat{\mathrm{j}}+\hat{\mathrm{k}}$, in an electromagnetic field given by $\overrightarrow{\mathrm{E}}=3 \hat{\mathrm{i}}+\hat{\mathrm{j}}+2 \hat{\mathrm{k}}, \overrightarrow{\mathrm{B}}=\hat{\mathrm{i}}+\hat{\mathrm{j}}-3 \hat{\mathrm{k}}$. The $\mathrm{y}$-component of the force experienced by $+\mathrm{q}$ is :-$2 \mathrm{q}$$11 q$$5 q$$3 q$Correct Option: , 2 Solution:...
Read More →Assuming human pupil to have a radius of
Question: Assuming human pupil to have a radius of $0.25 \mathrm{~cm}$ and a comfortable viewing distance of $25 \mathrm{~cm}$, the minimum separation between two objects that human eye can resolve at $500 \mathrm{~nm}$ wavelength is:-$100 \mu \mathrm{m}$$300 \mu \mathrm{m}$$1 \mu \mathrm{m}$$30 \mu \mathrm{m}$Correct Option: , 4 Solution:...
Read More →Three perfect gases at absolute
Question: Three perfect gases at absolute temperatures $\mathrm{T}_{1}, \mathrm{~T}_{2}$ and $\mathrm{T}_{3}$ are mixed. The masses of molecules are $\mathrm{m}_{1}, \mathrm{~m}_{2}$, and $\mathrm{m}_{3}$ and the number of molecules are $\mathrm{n}_{1}, \mathrm{n}_{2}$ and $\mathrm{n}_{3}$ respectively. Assuming no loss of energy, then final temperature of the mixture is :-$\frac{n_{1} T_{1}^{2}+n_{2} T_{2}^{2}+n_{3} T_{3}^{2}}{n_{1} T_{1}+n_{2} T_{2}+n_{3} T_{3}}$$\frac{n_{1}^{2} T_{1}^{2}+n_{2...
Read More →Two long parallel wires are at a distance
Question: Two long parallel wires are at a distance $2 \mathrm{~d}$ apart. They carry steady equal currents flowing out of the plane of the paper as shown. The variation of the magnetic field B along the line $\mathrm{XX}$ ' is given by:-Correct Option: , 2 Solution:...
Read More →Two beams, A and B ,
Question: Two beams, $\mathrm{A}$ and $\mathrm{B}$, of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam $\mathrm{A}$ has maximum intensity (and beam $\mathrm{B}$ has zero intensity), a rotation of polaroid through $30^{\circ}$ makes the two beams appear equally bright. If the initial intensitites of the two beams are $\mathrm{I}_{\mathrm{A}}$ and $\mathrm{I}_{\mathrm{B}}$ respectively, then $\frac{\mathrm{I}_{\m...
Read More →A thermally insulated vessel
Question: A thermally insulated vessel contains an ideal gas of molecular mass $M$ and ratio of specific heats $\gamma$. It is moving with speed $v$ and is suddenly broght to rest. Assuming no heat is lost to the surroundings, its temperature increases by :-$\frac{\gamma \mathrm{Mv}^{2}}{2 \mathrm{R}}$$\frac{(\gamma-1)}{2 \mathrm{R}} \mathrm{Mv}^{2}$$\frac{(\gamma-1)}{2(\gamma+1) \mathrm{R}} \mathrm{Mv}^{2}$$\frac{(\gamma-1)}{2 \gamma \mathrm{R}} \mathrm{Mv}^{2}$Correct Option: , 2 Solution:...
Read More →A particle moves with simple harmonic motion in a straight line.
Question: A particle moves with simple harmonic motion in a straight line. In first $\tau \mathrm{s}$, after starting from rest it travels a distance a, and in next $\tau \mathrm{s}$ it travels $2 \mathrm{a}$, in same direction, then : Amplitude of motion is 4 aTime period of oscillation is $6 \tau$Amplitude of motion is $3 \mathrm{a}$Time period of oscillation is $8 \tau$Correct Option: , 2 Solution:...
Read More →Two coherent point sources
Question: Two coherent point sources $S_{1}$ and $S_{2}$ are separated by a small distance 'd' as shown. The fringes obtained on the screen will be : pointsstraight lines semicirclesconcentric circlesCorrect Option: , 4 Solution:...
Read More →One kg of a diatomic gas
Question: One kg of a diatomic gas is at a pressure of $8 \times 10^{4} \mathrm{~N} / \mathrm{m}^{2}$. The density of the gas is $4 \mathrm{~kg} / \mathrm{m}^{3}$. What is the energy of the gas due to its thermal motion ?$6 \times 10^{4} \mathrm{~J}$$7 \times 10^{4} \mathrm{~J}$$3 \times 10^{4} \mathrm{~J}$$5 \times 10^{4} \mathrm{~J}$Correct Option: , 3 Solution:...
Read More →A beam of unpolarised light of intensity
Question: A beam of unpolarised light of intensity $\mathrm{I}_{0}$ is passed through a polaroid $\mathrm{A}$ and then through another polaroid $\mathrm{B}$ which is oriented so that its principal plane makes an angle of $45^{\circ}$ relative to that of $\mathrm{A}$. The intensity of the emergent light is :-$\mathrm{I}_{0}$$\mathrm{I}_{0} / 2$$\mathrm{I}_{0} / 4$$\mathrm{I}_{0} / 8$Correct Option: , 3 Solution:...
Read More →Due to the presence of the current
Question: Due to the presence of the current $\mathrm{I}_{1}$ at the origin:- A current loop $\mathrm{ABCD}$ is held fixed on the plane of the paper as shown in the figure. The arcs $\mathrm{BC}$ (radius $=b$ ) and DA (radius $=a$ ) of the loop are joined by two straight wires AB and CD. A steady current $\mathrm{I}$ is flowing in the loop. Angle made by $\mathrm{AB}$ and $\mathrm{CD}$ at the origin $\mathrm{O}$ is $30^{\circ}$. Another straight thin wire with steady current $I_{1}$ flowing out ...
Read More →This question has Statement-l and statement-2.
Question: This question has Statement-l and statement-2. Of the four choices given after the Statements, choose the one that best describes the two statements. Statement-1 : Davisson - Germer experiment established the wave nature of electrons. Statement-2: If electrons have wave nature, they can interfere and show diffraction.Statement-1 is true, Statement-2 is true and Statement-2 is the correct explanation for Statement-1.Statement-1 is true, Statement-2 is true and Statement-2 is not the cor...
Read More →In Young's double slit experiment, one of the slit is wider than other,
Question: In Young's double slit experiment, one of the slit is wider than other, so that the amplitude of the light from one slit is double of that from other slit. If $\mathrm{I}_{\mathrm{m}}$ be the maximum intensity, the resultant intensity I when they interfere at phase difference $\phi$ is given by :$\frac{I_{m}}{9}\left(1+8 \cos ^{2} \frac{\phi}{2}\right)$$\frac{\mathrm{I}_{\mathrm{m}}}{9}(4+5 \cos \phi)$$\frac{\mathrm{I}_{\mathrm{m}}}{3}\left(1+2 \cos ^{2} \frac{\phi}{2}\right)$$\frac{\m...
Read More →Three rods of Copper,
Question: Three rods of Copper, Brass and Steel are welded together to form a Y-shaped structure. Area of cross-section of each rod $=4 \mathrm{~cm}^{2}$. End of copper rod is maintained at $100^{\circ} \mathrm{C}$ where as ends of brass and steel are kept at $0^{\circ} \mathrm{C}$. Lengths of the copper, brass and steel rods are 46,13 and $12 \mathrm{cms}$ respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are $0.92...
Read More →The magnitude of the magnetic field (B) due to the loop
Question: The magnitude of the magnetic field (B) due to the loop $A B C D$ at the origin $(O)$ is :- A current loop $\mathrm{ABCD}$ is held fixed on the plane of the paper as shown in the figure. The arcs $\mathrm{BC}$ (radius $=b$ ) and DA (radius $=$ a) of the loop are joined by two straight wires AB and CD. A steady current $\mathrm{I}$ is flowing in the loop. Angle made by $\mathrm{AB}$ and $\mathrm{CD}$ at the origin $\mathrm{O}$ is $30^{\circ}$. Another straight thin wire with steady curr...
Read More →Direction : The question has a paragraph followed by two statement, Statement-1 and statement- 2 .
Question: Direction : The question has a paragraph followed by two statement, Statement-1 and statement- 2 . Of the given four alternatives after the statements, choose the one that describes the statements. A thin air film is formed by putting the convex surface of a plane-convex lens over a plane glass plate. With monochromatic light, this film gives an interference pattern due to light reflected from the top (convex) surface and the bottom (glass plate) surface of the film. Statement-1: When ...
Read More →The amplitude of a damped oscillator decreases to
Question: The amplitude of a damped oscillator decreases to $0.9$ times its original magnitude in $5 \mathrm{~s}$. In another $10 \mathrm{~s}$ it will decrease to a times its original magnitude, where a equals: $0.81$$0.729$$0.6$$0.7$Correct Option: , 2 Solution:...
Read More →If a piece of metal is heated to temperature
Question: If a piece of metal is heated to temperature $\theta$ and then allowed to cool in a room which is at temperature $\theta_{0}$ the graph between the temperature $\mathrm{T}$ of the metal and time $t$ will be closed to:Correct Option: , 3 Solution:...
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