If E and H
Question: If $\mathrm{E}$ and $\mathrm{H}$ represents the intensity of electric field and magnetising field respectively, then the unit of E/H will be :ohmmhojoulenewtonCorrect Option: 1 Solution: Unit of $\frac{E}{H}$ is $\frac{\text { volt } / \text { metre }}{\text { Ampere / metre }}=\frac{\text { volt }}{\text { Ampere }}=\mathrm{ohm}$...
Read More →Which of the following
Question: Which of the following is not a dimensionless quantity ?Relative magnetic permeability $\left(\mu_{\mathrm{r}}\right)$Power factorPermeability of free space $\left(\mu_{0}\right)$Quality factorCorrect Option: , 3 Solution: $\left[\mu_{r}\right]=1$ as $\mu_{\Gamma}=\frac{\mu}{\mu_{m}}$ $[$ power factor $(\cos \phi)]=1$ $\mu_{0}=\frac{\mathrm{B}_{0}}{\mathrm{H}}\left(\right.$ unit $\left.=\mathrm{NA}^{-2}\right):$ Not dimensionless $\left[\mu_{0}\right]=\left[\mathrm{MLT}^{-2} \mathrm{~A...
Read More →The following logic gate is equivalent to :
Question: The following logic gate is equivalent to : NOR GateOR GateAND GateNAND GateCorrect Option: 1 Solution: Truth table for the given logic gate: The truth table is similar to that of a NOR gate....
Read More →Which of the following statements are correct?
Question: Which of the following statements are correct? (A) Electric monopoles do not exist whereas magnetic monopoles exist. (B) Magnetic field lines due to a solenoid at its ends and outside cannot be completely straight and confined. (C) Magnetic field lines are completely confined within a toroid. (D) Magnetic field lines inside a bar magnet are not parallel. (E) $\chi=-1$ is the condition for a perfect diamagnetic material, where $\chi$ is its magnetic susceptibility. Choose the correct an...
Read More →There are
Question: There are $10^{10}$ radioactive nuclei in a given radioactive element, Its half-life time is 1 minute. How many nuclei will remain after 30 seconds ? $(\sqrt{2}=1.414)$$2 \times 10^{10}$$7 \times 10^{9}$ $10^{5}$$4 \times 10^{10}$Correct Option: , 2 Solution: $\frac{\mathrm{N}}{\mathrm{N}_{0}}=\left(\frac{1}{2}\right)^{\frac{\mathrm{t}}{\mathrm{t}_{1 / 2}}}$ $\frac{\mathrm{N}}{10^{10}}=\left(\frac{1}{2}\right)^{\frac{30}{60}}$ $\Rightarrow \quad \mathrm{N}=10^{10} \times\left(\frac{1}{...
Read More →In the given figure, the emf of the cell is
Question: In the given figure, the emf of the cell is $2.2 \mathrm{~V}$ and if internal resistance is $0.6 \Omega$. Calculate the power dissipated in the whole circuit : $1.32 \mathrm{~W}$$0.65 \mathrm{~W}$$2.2 \mathrm{~W}$$4.4 \mathrm{~W}$Correct Option: , 3 Solution: $\frac{1}{R_{e q}}=\frac{1}{4}+\frac{1}{8}+\frac{1}{12}+\frac{1}{6}=\frac{6+3+2+4}{24}=\frac{15}{24}$ $\mathrm{R}_{\mathrm{eq}}=\frac{24}{15}=1.6 \Rightarrow \mathrm{R}_{\mathrm{T}}=1.6+0.6=2.2 \Omega$ $\mathrm{P}=\frac{\mathrm{V}...
Read More →A uniformly charged
Question: A uniformly charged disc of radius $R$ having surface charge density $\sigma$ is placed in the xy plane with its center at the origin. Find the electric field intensity along the $\mathrm{Z}$-axis at a distance $\mathrm{Z}$ from origin :-$\mathrm{E}=\frac{\sigma}{2 \varepsilon_{0}}\left(1-\frac{\mathrm{Z}}{\left(\mathrm{Z}^{2}+\mathrm{R}^{2}\right)^{1 / 2}}\right)$$\mathrm{E}=\frac{\sigma}{2 \varepsilon_{0}}\left(1+\frac{\mathrm{Z}}{\left(\mathrm{Z}^{2}+\mathrm{R}^{2}\right)^{1 / 2}}\r...
Read More →A ball of mass 10 kg moving with a velocity
Question: A ball of mass 10 kg moving with a velocity $10 \sqrt{3} \mathrm{~ms}^{-1}$ along $\mathrm{X}$-axis, hits another ball of mass $20 \mathrm{~kg}$ which is at rest. After collision, the first ball comes to rest and the second one disintegrates into two equal pieces. One of the pieces starts moving along $\mathrm{Y}$-axis at a speed of $10 \mathrm{~m} / \mathrm{s}$. The second piece starts moving at a speed of $20 \mathrm{~m} / \mathrm{s}$ at an angle $\theta$ (degree) with respect to the...
Read More →In a photoelectric experiment ultraviolet light of wavelength
Question: In a photoelectric experiment ultraviolet light of wavelength $280 \mathrm{~nm}$ is used with lithium cathode having work function $\phi=2.5 \mathrm{eV}$. If the wavelength of incident light is switched to $400 \mathrm{~nm}$, find out the change in the stopping potential. ( $\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}$, $\left.\mathrm{c}=3 \times 10^{8} \mathrm{~ms}^{-1}\right)$ $1.3 \mathrm{~V}$$1.1 \mathrm{~V}$$1.9 \mathrm{~V}$$0.6 \mathrm{~V}$Correct Option: 1 Solution: $\mathrm{KE}...
Read More →Consider a frame that is made up of two thin massless rods AB and AC as shown in the figure.
Question: Consider a frame that is made up of two thin massless rods AB and AC as shown in the figure. A vertical force G P of magnitude 100 N is applied at point A of the frame Suppose the force is G P resolved parallel to the arms AB and AC of the frame. The magnitude of the resolved component along the arm AC is xN. The value of x, to the nearest integer, is________ $\left[\right.$ Given : $\sin \left(35^{\circ}\right)=0.573, \cos \left(35^{\circ}\right)=0.819$ $\left.\sin \left(110^{\circ}\r...
Read More →The resistance
Question: The resistance $\mathrm{R}=\frac{\mathrm{V}}{\mathrm{I}}$, where $\mathrm{V}=(50 \pm 2) \mathrm{V}$ and $\mathrm{I}=(20 \pm 0.2) \mathrm{A}$. The percentage error in $\mathrm{R}$ is ' $x$ ' \%. Sthe value of ' $x$ ' to the nearest integer is Solution: $\frac{\Delta \mathrm{R}}{\mathrm{R}} \times 100=\frac{\Delta \mathrm{V}}{\mathrm{V}} \times 100+\frac{\Delta \mathrm{I}}{\mathrm{I}} \times 100$ $\%$ error in $\mathrm{R}=\frac{2}{50} \times 100+\frac{0.2}{20} \times 100$ $\%$ error in $...
Read More →A bullet of mass 0.1kg is fired on
Question: A bullet of mass $0.1 \mathrm{~kg}$ is fired on a wooden block to pierce through it, but it stops after moving a distance of $50 \mathrm{~cm}$ into it. If the velocity of bullet before hitting the wood is 10 $\mathrm{m} / \mathrm{s}$ and it slows down with uniform deceleration, then the magnitude of effective retarding force on the bullet is ' $x$ ' $N$. The value of ' $x$ ' to the nearest integer is________. Solution: $\mathrm{v}^{2}=\mathrm{u}^{2}+2 \mathrm{as}$ $0=(10)^{2}+2(-a)\lef...
Read More →An npn transistor operates as a common emitter
Question: An npn transistor operates as a common emitter amplifier with a power gain of $10^{6}$. The input circuit resistance is $100 \Omega$ and the output load resistance is $10 \mathrm{~K} \Omega$. The common emitter current gain ' $\beta$ ' will be_______ . (Round off to the Nearest Integer) Solution: $10^{6}=\beta^{2} \times \frac{R_{0}}{R_{i}}$ $10^{6}=\beta^{2} \times \frac{10^{4}}{10^{2}}$ $\beta^{2}=10^{4} \Rightarrow \beta=100$...
Read More →As shown in the figure, a particle of mass 10
Question: As shown in the figure, a particle of mass 10 $\mathrm{kg}$ is placed at a point A. When the particle is slightly displaced to its right, it starts moving and reaches the point $B$. The speed of the particle at $\mathrm{B}$ is $\times \mathrm{m} / \mathrm{s}$. (Take $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}$ ) The value of ' $x$ ' to the nearest integer is_________. Solution: Using work energy theorem, $\mathrm{W}_{\mathrm{g}}=\Delta \mathrm{K} . \mathrm{E}$ $(10)(g)(5)=\frac{1}{2}(1...
Read More →In the logic circuit shown in the figure, if input A and B are 0 to 1 respectively,
Question: In the logic circuit shown in the figure, if input A and B are 0 to 1 respectively, the output at Y would be 'x'. The value of x is _______. Solution:...
Read More →A ball of mass 10kg moving with a velocity
Question: A ball of mass $10 \mathrm{~kg}$ moving with a velocity $10 \sqrt{3} \mathrm{~m} / \mathrm{s}$ along the $\mathrm{x}$-axis, hits another ball of mass $20 \mathrm{~kg}$ which is at rest. After the collision, first ball comes to rest while the second ball disintegrates into two equal pieces. One piece starts moving along $y$-axis with a speed of 10 $\mathrm{m} / \mathrm{s}$. The second piece starts moving at an angle of $30^{\circ}$ with respect to the x-axis. The velocity of the ballmov...
Read More →A particular hydrogen like ion emits radiation of frequency
Question: A particular hydrogen like ion emits radiation of frequency $2.92 \times 10^{15} \mathrm{~Hz}$ when it makes transition from $\mathrm{n}=3$ to $\mathrm{n}=1$. The frequency in $\mathrm{Hz}$ of radiation emitted in transition from $\mathrm{n}=2$ to $\mathrm{n}=1$ will be:$0.44 \times 10^{15}$$6.57 \times 10^{15}$$4.38 \times 10^{15}$$2.46 \times 10^{15}$Correct Option: , 4 Solution: $\mathrm{nf}_{1}=\mathrm{k}\left(\frac{1}{1}-\frac{1}{3^{2}}\right)$ $\mathrm{nf}_{2}=\mathrm{k}\left(1-\...
Read More →A sinusoidal voltage of peak value 250 V is applied to a series LCR circuit,
Question: A sinusoidal voltage of peak value $250 \mathrm{~V}$ is applied to a series LCR circuit, in which $\mathrm{R}=8 \Omega, \mathrm{L}=24 \mathrm{mH}$ and $\mathrm{C}=60 \mu \mathrm{F}$. The value of power dissipated at resonant condition is ' $\mathrm{x}$ ' $\mathrm{kW}$. The value of $\mathrm{x}$ to the nearest integer is____________ Solution: At resonance power $(\mathrm{P})$ $\mathrm{P}=\frac{\left(\mathrm{V}_{\mathrm{tms}}\right)^{2}}{\mathrm{R}}$ $P=\frac{(250 / \sqrt{2})^{2}}{8}=390...
Read More →Identify the logic operation carried out by the given circuit :-
Question: Identify the logic operation carried out by the given circuit :- OR$\mathrm{AND}$NORNANDCorrect Option: , 3 Solution: Option (3)...
Read More →The value of power dissipated across the zener diode
Question: The value of power dissipated across the zener diode $\left(\mathrm{V}_{\mathrm{z}}=15 \mathrm{~V}\right)$ connected in the circuit as shown in the figure is $x \times 10^{-1}$ watt. The value of x, to the nearest integer, is ______. Solution: Voltage across $R_{S}=22-15=7 V$ Current through $\mathrm{R}_{\mathrm{S}}=\mathrm{I}=\frac{7}{35}=\frac{1}{5} \mathrm{~A}$ Current through $90 \Omega=\mathrm{I}_{2}=\frac{15}{90}=\frac{1}{6} \mathrm{~A}$ Current through zener $=\frac{1}{5}-\frac{...
Read More →A series LCR circuit driven by
Question: A series LCR circuit driven by $300 \mathrm{~V}$ at a frequency of $50 \mathrm{~Hz}$ contains a resistance $\mathrm{R}=3 \mathrm{k} \Omega$, an inductor of inductive reactance $X_{L}=250 \pi \Omega$ and an unknown capacitor. The value of capacitance to maximize the average power should be : $\left(\right.$ Take $\left.\pi^{2}=10\right)$ $4 \mu \mathrm{F}$$25 \mu \mathrm{F}$$400 \mu \mathrm{F}$$40 \mu \mathrm{F}$Correct Option: 1 Solution: For maximum average power $\mathrm{X}_{\mathrm{...
Read More →An inductor coil stores
Question: An inductor coil stores $64 \mathrm{~J}$ of magnetic field energy and dissipates energy at the rate of $640 \mathrm{~W}$ when a current of $8 \mathrm{~A}$ is passed through it. If this coil is joined across an ideal battery, find the time constant of the circuit in seconds:$0.4$$0.8$$0.125$$0.2$Correct Option: , 4 Solution: $\mathrm{U}=\frac{1}{2} \mathrm{Li}^{2}=64 \Rightarrow \mathrm{L}=2$ $i^{2} R=640$ $\mathrm{R}=\frac{640}{(8)^{2}}=10$ $\tau=\frac{L}{R}=\frac{1}{5}=0.2$ Option (4)...
Read More →An electric appliance supplies
Question: An electric appliance supplies $6000 \mathrm{~J} / \mathrm{min}$ heat to the system. If the system delivers a power of $90 \mathrm{~W}$. How long it would take to increase the internal energy by $2.5 \times 10^{3} \mathrm{~J}$ ?$2.5 \times 10^{2} \mathrm{~s}$$4.1 \times 10^{1} \mathrm{~s}$$2.4 \times 10^{3} \mathrm{~s}$$2.5 \times 10^{1} \mathrm{~s}$Correct Option: 1 Solution: $\Delta \mathrm{Q}=\Delta \mathrm{U}+\Delta \mathrm{W}$ $\frac{\Delta \mathrm{Q}}{\Delta \mathrm{t}}=\frac{\De...
Read More →Seawater at a frequency
Question: Seawater at a frequency $f=9 \times 10^{2} \mathrm{~Hz}$, has permittivity $\varepsilon=80 \varepsilon_{0}$ and resistivity $\rho=0.25 \Omega \mathrm{m}$. Imagine a parallel plate capacitor is immersed in seawater and is driven by an alternating voltage source $\mathrm{V}(\mathrm{t})=\mathrm{V}_{0} \sin (2 \pi \mathrm{ft})$. Then the conduction current density becomes $10^{\mathrm{x}}$ times the displacement current density after time $\mathrm{t}=\frac{1}{800} \mathrm{~s}$. The value o...
Read More →A parallel plate capacitor has plate area
Question: A parallel plate capacitor has plate area $100 \mathrm{~m}^{2}$ and plate separation of $10 \mathrm{~m}$. The space between the plates is filled up to a thickness 5 $\mathrm{m}$ with a material of dielectric constant of 10 . The resultant capacitance of the system is ' $x^{\prime} \mathrm{pF}$. The value of $\varepsilon_{0}=8.85 \times 10^{-12} \mathrm{~F} . \mathrm{m}^{-1}$. The value of ' $x$ ' to the nearest integer is__________. Solution: $A=100 \mathrm{~m}^{2}$ Using $\mathrm{C}=\...
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