0 views

In a uniform magnetic field of induction B, a wire, in the form of semicircular of radius ‘R’, rotates about the diameter of the circle with an angular speed 'ω' . The axis of rotation is perpendicular to the field. If the total resistance of the circuit is R’, the near power generated per period of rotation is (1) \(\frac{B\pi R^2 ω}{2R'}\) (2) \(\frac{(B\pi R^2 ω)^2}{8R'}\) (3) \(\frac{(B\pi Rω)^2}{8R'}\) (4) \(\frac{B\pi R^2ω^2}{8R'}\)

asked
Jan 13
by
anonymous

0 views

**Description :** A circular coil, of radius a, (having N turns) is made to rotate about its vertical diameter with an angular speed ω. The coil is present in a region where a uniform horizontal magnetic field B is present. If the coil has a resistance ... a^2 ωB}{\sqrt{2}R}\) and \(\frac{(N\pi a^2 ωB)}{\sqrt{2}R}\)

0 views

**Description :** A straight rod PQ, of length L, is rotating about an axis passing through O' and perpendicular to its plane. The rod rotates in a uniform (and normal) magnetic field B, with an angular speed ω (The point O' is at a perpendicular ... {BωL^2}{4}\) (3) \(\frac{BωL^2}{3}\) (4) \(\frac{1}{2}BωL^2\)

0 views

**Description :** A planar circular coil, of radius a, has N turns and it can be made to rotate about its diameter as axis. The coil has a resistance R and is present in a region where a uniform magnetic field, B ... spin' at start, it would then keep on rotating at its initial rate, due to its rotational inertia'.

0 views

**Description :** An A.C. voltage source (v = v0 sin ωt) , is connected across a series LCR Circuit. If the values of L and C, in the circuit, equal \((\frac{2\sqrt{3}R}{ω})\) and \((\frac{1}{\sqrt{3}(Rω)})\) respectively; the phase ... ((\frac{1}{\sqrt{2}})\) (4) \((\frac{\pi}{3})\) and \((\frac{\sqrt{3}}{6})\)

0 views

**Description :** A uniform magnetic field B exists in a cylindrical region of radius 0.1 m as shown in the figure. A uniform wire of length 0.80 m and resistance 4.0Ω is bent into a square frame and is placed with one side along a diameter ... frame. [Hint: |ε|= \(\frac{dϕ_B}{dt}=\frac{1}{2}\pi^2\frac{dB}{dt}\) ]

0 views

**Description :** A rectangular coil, of 300 turns, has an average area of 25 cm x 10 cm. The coil rotates, with a speed of 50 cycles per second, in a uniform magnetic field of 4 x 10-2T, about an axis perpendicular to the field. The peak value of induced emf (in volt), is (1) 3 π (2) 30 π (3) 300 π (4) 3000 π

0 views

**Description :** A thin semicircular conducting ring, of radius R, in falling with its plane vertical in a uniform horizontal magnetic field of strength B. At the position MNQ the speed of the ring is V. The potential ... higher potential (3) 2RBV, with Q at higher potential (4) 2R2BV, with M at higher potential

0 views

**Description :** A conducting circular loop is placed in a uniform magnetic filed (of induction B'tesla), with its plane normal to the field. If the radius of the loop were to start shrinking at a constant rate dr/dt. The induced emf, at the instant ... {dr}{dt})B\) (4) \(-\frac{1}{2}\pi r^2 B(\frac{dr}{dt})B\)

0 views

**Description :** A mini generator has a coil of 1000 turns, each of area 10-2m2 . The coil is placed with its plane perpendicular to a uniform magnetic field of intensity 25 mT and is rotated at a uniform rate of 100 rotations per ... 3) 100 volt, 0 volt, 100 volt, 0 volt (4) 100 volt, 100 volt, 100 volt, 100 volt

0 views

**Description :** A conducting circular loop is placed in a uniform magnetic field B = 0.25 T, with its plane perpendicular to the field. The radius of the loop is made to shrink at a constant rate of 1 mm/s. The induced emf, when the radius is 2 cm, ... })μV\) (2) \((\pi)μV\) (3) \((2\pi)μV\) (4) \((2.5)\pi μV\)

0 views

**Description :** A uniform disc of mass M, radius R is rotating in a horizontal plane about its own axis with a constant angular speed ω0 . A ring of mass M/2 ; radius R/2 is initially at rest. The ring is gently placed coincentrically on rotating ... \) (3) \(\frac{MR^2ω^2_ 0}{5}\) (4) \(\frac{MR^2ω^2_ 0}{4}\)

0 views

**Description :** The set-up, shown in the figure, is present in a uniform magnetic field, B, directed perpendicular to the plane of this set-up'. The rod, PQ, of length L, is allowed to slide down vertically, under its own weight, on the (shaded) ... })\) (3) \((\frac{B^2l^2}{mgR})\) (4) \((\frac{mgR}{B^2l^2})\)

0 views

**Description :** Two circular loops, of radii R and r (R >> r), respectively, are positioned, parallel to each other, in the yz plane. The centres and axis, of both the loops, lie on the x-axis, a distance x apart. The larger loop has N turns, ... {μ_0\pi}{2x^2}(nN)(Rr^2)\) (4) \(\frac{μ_0\pi}{2x^3}(nr^2)(NR^2)\)

0 views

**Description :** The magnetic flux ϕ , through a stationary loop of wire, having a resistance R, varies with time as ϕ = (at2 + bt) where a and b are positive constants. The average emf, and the total charge flowing in the loop in the time interval t ... b \tau}{R})\) (4) \(2(a\tau +b),(\frac{a\tau ^2+b \tau}{2R})\)

0 views

**Description :** A particle moves in x-y plane in a circular path of radius R with a constant angular velocity ω . At t = t, the radius vector joining particle with centre of circle makes an angle θ with x-axis. The instantaneous linear velocity v ... )\(\hat{i}\) - (Rω sinθ) (4) (-Rω sinθ) - (Rω sinθ)\(\hat{j}\)

0 views

**Description :** A solid conducting sphere, of radius R and total charge q, rotates about its diametric axis with a constant angular speed 'ω' . The equivalent magnetic moment of the sphere is (1) 1/3 qR2 ω (2) 2/3 qR2 ω (3) 1/5 qR2 ω (4) 2/5 qR2 ω

0 views

**Description :** A very small circular loop of area 5 x 10-4m2 , resistance 2 ohm and negligible inductance, is initially coplanar and cocentric, with a much larger fixed circular loop of radius 0.1m. A constant ... diameter. Calculate the induced emf and induced current, as a function of time, in the smaller loop.

0 views

**Description :** A rigid wire consists of semicircular portion of radius R' and two straight sections as shown in figure. It is present in a uniform perpendicular magnetic field B'. The magnetic force on the wire, when it carries a ... (1) (2i RB) upward (2) (2iRB) downward (3) (iπRB) upward (4) (iπRB) downward

0 views

**Description :** A long cylindrical conductor, of radius a', has two cylindrical cavities of diameter a', through its entire length, as shown in cross section in figure. A current I is directed out of the page and is uniform throughout the cross ... \(\frac{μ_0I}{2\pi r}[\frac{2r^2 +a^2}{4r^2 + a^2}]\) downwards

0 views

**Description :** A uniform disc of mass 2m, radius R is at rest in a vertical position. It is free to rotate about a horizontal axis through center O. A particle of m moving with speed v is aimed towards the edge of the disc as shown in ... gets embedded is (neglect gravity) (1) v/R (2) v/2R (3) 2v/R (4) 3/2 v/R

1 view

**Description :** A (infinite) long straight wire, carrying a current I, is placed parallel to the x-axis. If a straight conductor, of length l , positioned along the y-axis, as shown, starts moving with a uniform velocity v = v\(\hat{i}\) , the ... +\frac{l}{a})\) (4) \(\frac{μ_0Iv}{2\pi}\frac{l}{(a+\frac{l}{2})}\)

0 views

**Description :** A conducting loop of area 5.0 cm2 is placed in a magnetic field which varies sinosoudally with time as B = B0 sin ωt where B0 = 0.20 T and ω 300/s, such that the normal to the coil makes an angle of 60° with ... ) the maximum emf induced in the coil (b) the emf induced at \(t =(\frac{\pi}{600})s.\)

0 views

**Description :** A conducting wire xy, of mass m, (and negligible resistance) slides smoothly on two parallel conducting wires as shown in the diagram. The closed circuit has resistance R' due to side AC. Sides AB and CD are perfect conductors. If ... frac{l^2B^2}{mR}\frac{dx}{dt}+\frac{l^2B}{mR}\frac{dB}{dt}x(t)\)

0 views

**Description :** Instantaneous voltage of the amplitude modulated wave is given by \(\nu_{AM}=V_c(1+m\,sin\,ωt)sin\,ω_ct\) Assuming that the effective resistance of the modulator circuit is R, the total power of the amplitude modulated wave will be equal ... {m^2V^2_C}{4R}\) (4) \(\frac{V^2_c}{2R}[\frac{1+m^2}{2}]\)

0 views

**Description :** A uniformly charged disc, whose total charge has a magnitude ‘q’, and whose radius is ‘r’, rotates with a constant angular velocity of magnitude 'ω'. The magnetic dipole moment of the ring is (1) \(\frac{qωr^2}{4}\) (2) \(\frac{qωr^2}{2}\) (3) \(\frac{qωr^2}{8}\) (4) \(qωr^2\)

0 views

**Description :** A rod of mass M; length L is made of material of Young's modulus Y. The rod rotates in a horizontal plane about an axis through its one end and perpendicular to length of rod with a constant angular speed ω. The increase in length of ... (\frac{pω^2}{Y})L^3\) (d) \(\frac{2}{3}(\frac{pω^2}{Y})L^3\)

0 views

**Description :** A rod, PQ, of length l , slides with a constant velocity on two conducting rails. The system of the rod and conducting rails, is present in a region where a uniform (normal) magnetic field, of strength B, is present. The two ... {16Ri_0}{Bl}\) (3) \(\frac{Bl}{(16Ri_0)}\) (4) \(\frac{3Bl}{(16Ri_0)}\)

0 views

**Description :** A sinusoidal A.C. voltage source, of adjustable frequency, is connected across a series LCR' combination. The inductance (L) and the capacitance (C), present in the circuit, can be expresssed in terms of the quality factor (Q) the ... \(L=\frac{1}{ω_0Q^2R^2}\) and \(C = (\frac{Q^2R^2}{ω_0})\)

0 views

**Description :** A uniform disc of mass 2m radius R is pivoted at its center O on a smooth horizontal surface. The disc in free to rotate about a vertical axis ZOZ´ through its center O. The disc is initially at rest. A particle of mass m is moving ... \(\frac{2v}{R};\frac{v}{R}\) (4) \(\frac{2v}{R};\frac{v}{2R}\)

0 views

**Description :** A uniform cylinder of mass M, radius R is rotating about its own axis with a speed of n r.p.s. It is gently placed against a corner as shown in Fig.. Coefficient of freection between walls and cylinder is μ. The number of revolutions ... {48\pi^2μg(μ+1)}\) (4) \(\frac{n^2R(μ^2+1)}{32\pi^2μg(μ-1)}\)

0 views

**Description :** A voltage source, v = v0 sin ωt, is connected across a series LCR circuit. The values of L and C, in the circuit, equal \(\frac{9R}{ω}\) and \(\frac{1}{10Rω}\) , The phase angle (between the current and voltage in ... ) and \(3\sqrt{10}\) (4) \(\frac{\pi}{4}\) (Current lagging) and \(2\sqrt{10}\)

0 views

**Description :** A charge ‘q’ is uniformly distributed on a non-conducting disc, of radius R, it is rotated with angular speed 'ω' about an axis passing through the centre of mass of the disc and perpendicular to its plane. The magnetic moment of the disc will be (1) 1/4 ωqR2 (2) 1/2 ωqR2 (3) ωqR2 (4) 1/8 ωqR2

0 views

**Description :** A 10 meter long wire is kept in east west direction. It is falling down with a speed of 5 m/s, perpendicular to the horizontal component of earth's magnetic field of 0.30 x 10-4 Wb/m2 . (i) what ... .d induced between the ends of the wire? (ii) which end of the wire will be at a higher potential?

0 views

**Description :** A uniform Catherine Wheel consists of many thin circular turns of a combustible material. The wheel is free to rotate about a vertical axis through its center in a horizontal plane. The combustile material burns at a constant ... (\frac{4\pi FσR}{M_1\alpha}\) (4) \(\frac{2\pi FσR}{M_1\alpha}\)

0 views

**Description :** A conducting ring, of radius r, is placed in a varying magnetic field perpendicular to the plane of the ring. If the rate at which the magnetic field, varies, is x, the (average) electric field intensity, at any point of the ring, would be (1) r x (2) rx/2 (3) 2rx (4) 4r/x

0 views

**Description :** A uniform (normal) magnetic field, B, bends the path of the most energatic photoelectrons, (emitted from a given photosensitive surface due to the action of monochromatic radiations of wave length λ ) into a circle of radius r. The work ... 2r^2}{2m}]\) (4) \([\frac{hc}{λ}+\frac{e^2B^2r^2}{2m}]\)

0 views

**Description :** A small coil, having n turns each of (everage) radius r, is held normal to the magnetic field liens in the region between the (flat) pole pieces of a horse shoe magnet. The terminals ofthe coil are connected to a ... the magnetic field), is the graph labelled as graph. (1) K (2) L (3) M (4) N

0 views

**Description :** A wire of mass m is bent into an equilateral triangle of side l . Two beads (identical) each of mass m0 can slide freely along sides PQ and QR of triangle. The triangle is set into ... i.e. sum of kinetic and potential energy) and total angular momentum (4) Kinetic energy and angular momentum

0 views

**Description :** The magnetic flux, through a coil, present in a magnetic field, directed perpendicular to its plane, varies with time (in second) according to the relation. ϕB = 6t2 + 7t + 1 (ϕB in miliweber) Find the ... at t = 2s. Also find the current, and its direction, in the resistance R, if R = 10Ω

0 views

**Description :** In A.C. voltage source, v = v0 sin t; having a fixed value for v0 , but of variable frequency, is connected across a given series LCR circuit. The variation of the current I, flowing in the circuit, ... ω0 and the difference, (ω2- ω1) , increases with an increase in the Q-factor' of the circuit

0 views

**Description :** In A.C. voltage source, v = v0 sin t; having a fixed value for v0 , but of variable frequency, is connected across a given series LCR circuit. The variation of the current I, flowing in the circuit, ... ω0 and the difference, (ω2- ω1) , increases with an increase in the Q-factor' of the circuit

0 views

**Description :** A regular polygon of n-sides is formed by bending a wire of total length 2πr. If this wire now carries a current i, the magnetic field B, at the centre of this polygon, would be (1) \(\frac{μ_0in^2 sin^2 (\pi /n)}{2r^2 \pi ... (3) \(\frac{μ_0in^2 sin^2 (\pi /n)}{2\pi^2 r \,cos (\pi / n)}\) (4) zero

0 views

**Description :** A thin uniform rod AB of mass 2m has length 2L. The rod is pivoted at midpoint O on a smooth horizontal surface. A particle P of mass m moving with speed v0 as shown in Fig ; hits rod at point C and sticks to it. The rod-mass ... ) (3) \(v_0=\frac{7}{12}\sqrt{ω}L\) (4) \(v_0=\frac{5}{12}\sqrt{ω}L\)

0 views

**Description :** A given AC source, v = v0 sin ωt, is connected across a given series LCR circuit. The graph, showing simultaneously, the variation of the voltage and current in the circuit, with time, has the form shown. The current, ... ) (4) \((\frac{ω^2 C}{1-ω^2LC})\) in series with the given inductor (L)

0 views

**Description :** An electric current i' enters, and leaves, a uniform circular wire of radius a' through diametrically opposite points, A charged particle q, moving along the axis of circular wire, passes through its centre at speed v'. The ... \(qv\,\frac{μ_0i}{4a}\) (3) \(qv\frac{μ_0i}{2\pi a}\) (4) zero

0 views

**Description :** A series LCR circuit is connected to an a.c. voltage source (v = v0 sinωt) and the value of C is such that 1/ωC ≃ 0. The phase angle (θ), between the current flowing and the voltage applied, then equals. (1 ... tan-1 (1/ωR); current lagging; θ can be made zero by taking a value of C equal to (1/ω2L)

0 views

**Description :** A wire of uniform resistance z r m-1 is sent into a circle of radius r. The same wire is connected between point A and B as shown. The equivalent resistance between A and B is (1) \(\frac{Zr}{(3\pi +16)}\) (2) \(\frac{6\pi (z/ ... (3) \(\frac{6\pi z r}{(3\pi + 16)}\) (4) \((\frac{z}{r})(3\pi + 16)\)

0 views

**Description :** A thin wire of uniform linear density λ is bent into a semi-circle of radius R. What is the intensity of gravitational field at center O? (1) \(\frac{2GM}{R^2}j\) (2) \(\frac{2GM}{\pi R^2}j\) (3) \(\frac{\sqrt{2}GM}{R^2}j\) (4) \(\frac{3GM}{R^2}j\)

0 views

**Description :** A 100 turn, closely wound circular coil, of mean radius 10cm, carries a current of 3.2 A. The coil is placed in a vertical plane and is free to rotate about a horizontal direction which ... the influence of the magnetic field. Calculate the torque in the initial and final position of the coil.

0 views

**Description :** Consider two coplanar, co-centric circular coils having radius r1 and r2 (r2 > r1) as shown in the figure. The mutual inductance between these two coils will be (1) \(\frac{μ_0\pi r^2_1}{2r_2}\) (2) \(\frac{μ_0\pi r_1}{2r_2}\) (3) \(\frac{μ_0\pi r^2_2}{2r_2}\) (4) \(\frac{μ_0\pi r^2_1}{2r_1}\)

...