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Answers posted by suganyadevi.p
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If $( \overrightarrow a \: and \: \overrightarrow b)$ are two vectors such that $( | \overrightarrow a. \overrightarrow b| = | \overrightarrow a x \overrightarrow b |)$, then what is the angle between $( \overrightarrow a \: and \: \overrightarrow b)?$
answered
Feb 16, 2017
Given : $( | \overrightarrow a. \overrightarrow b| = | \overrightarrow a x \overrightarrow b |)$$|...
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Solve the differential equation : $(x+y)dy + (x-y) dx=0$
answered
Feb 16, 2017
Given : $(x+y)dy + (x-y) dx=0$$ (x + y) dy = -(x - y) dx $$ \frac {dy}{dx} = \frac {-(x - y)}{(x + y...
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If vectros $ \overrightarrow a = 2\hat i + 2\hat j +3\hat k , \overrightarrow b = -\hat i + 2\hat j +\hat k \: and \: \overrightarrow c = 3\hat i + \hat j $ are such that $( \overrightarrow a +\lambda \overrightarrow b)$ is perpendicular to $( \overrightarrow c )$, then find the value of $( \lambda )$
answered
Feb 16, 2017
Let $ \overrightarrow a = 2\hat i + 2\hat j +3\hat k , \overrightarrow b = -\hat i + 2\hat j +\hat...
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Antibody found in the blood after antigen stimulation and also has the ability to cross placenta is
answered
Jan 9, 2017
Ans: (D) IgA
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The gene gun method employs high velocity particles of ____
answered
Jan 9, 2017
Ans: (C) Tungsten
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write the corresponding RNA sequence for 3' ATGCATG 5'
answered
Jan 9, 2017
( a ) 5' UACGUAC 3'
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the helicity of the DNA is stable due
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Jan 9, 2017
The plane of one base pair stacks over the other in a double helix and hydrogen bonds confer stabili...
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During a cell division ___ takes place
answered
Jan 9, 2017
Ans: (D) both c and b
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Which plasmid vector has polycloning site consists of a tandem array of unique cleavage sites for 13 restriction enzymes: HindIIl, Spill, Pstl, SaiL Acd, HitlelI, Xiln!, BmnHI, Sma!, Xmal, Kpl1I, Sad, and EcoRl ?
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Jan 9, 2017
Ans: ( B ) pBR322pBR322 is a plasmid and was one of the first widely used E. coli cloning vectors. ...
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PCR can be used to detect
answered
Jan 9, 2017
Ans: (D) all of the above
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Identify the procedure showm in the picture:
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Jan 9, 2017
Ans: (A) Vasectomy In vasectomy small part of the vas deferns is removed or tied up through a small ...
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During an allergic response ___ is/are released from the mast cells
answered
Jan 9, 2017
Ans: (D) Both b and c
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Identify the teeth marked as A, B, C, D their count in adult human and also the structure marked as E in order in the picture :
answered
Jan 9, 2017
Ans: (B) incisor-2, canine-1, premolar-2, molar-3; socket of jaw
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Who proposed the operon model for the regulation of transcription ?
answered
Jan 6, 2017
Ans: ( D ) Jacob and Monod, 1961
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A magnetic field in a certain region is given by $ B = B_0 cm (\omega t) \hat {k}$ and a coil of radius "a" with resistance R is placed in the x - y plane with its centre at the origin in the magnetic field, as shown in the fig. Find the magnitude and th direction of the current at (a, 0, 0) at $ t = \frac {\pi}{2\omega} \; and \; t = \frac {3 \pi}{2 \omega}$
answered
Dec 30, 2016
Given: $\overrightarrow B = B_0 \; cm (\omega t)\hat {k}$(ie) magnetic field along positive Z axisMa...
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A rectangular loop of wire ABCD is kept close to an infinitely long wire carrying a current $ I (t) = I_0 (1 - \frac {t}{T}) for $ 0 \leq t \leq T$ and $ I (0) = 0$ for t > T, as shown in the fig. Find the total charge passing through a given point in the loop, in time T, The resistance of the loop is R.
answered
Dec 30, 2016
In the fig, XY is an infinitely long wire carrying current $ I (t) = \frac {I_0}{1 - \frac{t}{T}}$ f...
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Consider an infinitely long wire carrying a current I(t), with $ \frac {dI}{dt} = \lambda = constant$. Find the current produced in the rectangular loop of wire ABCD if its resistance is R, as shown in the fig.
answered
Dec 30, 2016
Xy is infinitely long wire carrying current I (t) such that $\frac {dI}{dt} = \lambda = constant$At ...
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A magnetic field B is confined to a region $r \leq a$ and points out the paper (the Z axis) $ r = 0$ being the centre of the circular region. A charged ring (charge = Q) of radius b $b>a$ and mass m lies in the xy plane with its centre at the origin. the ring is free to rotate and is at rest. The magnetic field is brought to zero in time $\bigtriangleup t$. Find the angular velocity $\omega$ of the ring after the field vanister.
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Dec 30, 2016
If E is the electric field generated around the charged ring of radius b, then $e = \frac {d\phi}{dt...
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Give the expression for average value of a.c voltage $V = V_0\; sin \omega t$ over time interval $ t = 0 \; to \; t = \frac {\pi}{\omega}$
answered
Dec 30, 2016
When $ t = \frac {\pi}{\omega} = \frac {1}{2} . \frac {2\pi}{\omega} = \frac {1}{2}T$Hence the avera...
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An electrical element x connected to an alternating voltage source has current through it leading the voltage by $\frac {\pi}{2}$ radius. Identify x and write an expression for its reactance.
answered
Dec 30, 2016
Current leads the alternating voltage by $\frac {\pi}{2}$ radian. Hence X is pure capacitance.$X_c =...
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Self induction of an air core inductor increases from 0.01 MH to 10 MH on introducing an iron core into it. What is the relative permeability of the core used?
answered
Dec 30, 2016
$ L_0 = 0.01\; MH = 10^{-5} H$$ L = 10 \; MH = 10^{-2} H$$ \mu r = \frac {L}{L_0} = \frac {10^{-2}}...
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The dimension of $\frac {h}{e}$ is the same as that of magnetic flux $\phi$. Say true or false.
answered
Dec 30, 2016
True.$ \frac {h}{e} = \frac {Joule - sec}{coulomb} = \frac {Joule}{Ampere} = Magnetic\; flux$
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The dimensions of electric and magnetic flux are same. Say true or false.
answered
Dec 30, 2016
False. Dimension formula for electric flux = $ ML^3 T^{-3} A^{-1}$Dimension formula for magnetic flu...
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A coil of a metal wire is kept stationary in a non - uniform magnetic field. An emf is induced in the coil. Say true or false.
answered
Dec 30, 2016
False. Magnetic flux does not change with time here
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A magnetic field of 10T acts normal to a coil of 50 turns having $100 cm^2$ area. Find emf induced if the coil is removed from magnetic field in 0.1 sec.
answered
Dec 30, 2016
$ B = 10T$$ N = 50 \; turns, A = 100 cm^2 = 10^{-2} m^2$$ t = 0.1 sec$$ \theta = 0^\circ$$ \phi = N ...
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A circular copper disc 10 cm in radius rotates at $20\pi$ rad/s about an axis through its centre and perpendicular to its disc. A uniform magnetic field of 0.2T acts perpendicular to the disc. Calculate the induced current if the resistance of the disc is $2\Omega$.
answered
Dec 30, 2016
$ i = \frac {\varepsilon}{R} = \frac {\frac{1}{2} B \omega l^2}{R}$$ = \frac {\frac{1}{2} \times 0.2...
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A circular copper disc 10 cm in radius rotates at $20\pi$ rad/s about an axis through its centre and perpendicular to its disc. A uniform magnetic field of 0.2T acts perpendicular to the disc. Calculate the potential difference developed between the axis of the disc and the rim.
answered
Dec 30, 2016
Given: $\omega = 20\pi \;rad/s$$ l= 10 cm = 0.1 m$$ B = 0.2T$$ R = 2 \Omega$$ \varepsilon = \frac {1...
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A wheel with 50 metallic spokes each 0.5 m long is rotated with an angular speed of 12 radian /sec, in a plane normal to the earth's magnetic field. If the magnitude of the field is $ 0.5 \times 10^{-4}$ T, calculate the emf induced between the axle and the rim of the wheel.
answered
Dec 30, 2016
No. of spokes = 50$ l = 0.5 m$$\omega = 12 rad /sec$$ B = 0.5 \times 10^{-4} T$$ \varepsilon = \frac...
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A cylindrical bar magnet is kept along the axis of a circular coil and near it as shown in the fig. Will there be any induced e.m.f at the terminals of the coil, when the magnet is rotated about an axis perpendicular to the length of the magnet?
answered
Dec 30, 2016
Yes. Due to the change in magnetic flux, emf is induced.
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A cylindrical bar magnet is kept along the axis of a circular coil and near it as shown in the fig. Will there be any induced e.m.f at the terminals of the coil, when the magnet is related about its own axis.
answered
Dec 30, 2016
No. Since there is no change in magnetic flux, there is no emf induced in the coil.
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A circular coil of radius 8.0 cm and 20 turns rotates about its vertical diameter with an angular speed of $ 50 rad s^{-1}$ in a uniform horizontal magnetic field of magnitude $ 3 \times 10^{-2} T$. It the coil forms a closed loop of resistance $ 10 \Omega$, calculate the power dissipated as heat.
answered
Dec 30, 2016
$ I_0 = \frac {E_0}{R} = \frac {NBA \omega}{R} = \frac {20 \times 3 \times 10^{-2} \times 3.14 \time...
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A circular coil of radius 8.0 cm and 20 turns rotates about its vertical diameter with an angular speed of $ 50 rad s^{-1}$ in a uniform horizontal magnetic field of magnitude $ 3 \times 10^{-2} T$. Calculate the average emf.
answered
Dec 30, 2016
Average value of the emf induced = 0
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A circular coil of radius 8.0 cm and 20 turns rotates about its vertical diameter with an angular speed of 50 $rad s^{-1}$ in a uniform horizontal magnetic field of magnitude $ 3 \times 10^{-2} T$. Calculate the maximum emf induced in the coil.
answered
Dec 30, 2016
Given: $ r = 8.0 cm = 8 \times 10^{-2} m$$ A = \pi r^2 = 64 \times 10^{-4} \pi m^2$$ N = 20$$ \omega...
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Write a expression for mutual inductance of two coaxial solenoids.
answered
Dec 30, 2016
$ M = \frac {\mu_0 N_1 N_2 A}{Al} ; \;\;$ A is the area of cross section of inner solenoid and l is ...
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Why are resistance coils usually double wound?
answered
Dec 30, 2016
To avoid induction effects, magnetic field due to current in one half of the coil is cancelled by ma...
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The rate of charge of magnetic flux has same units as induced e.m.f. Say true or false.
answered
Dec 30, 2016
True.Dimension for induced e.m.f is $ ML^2 T^{-3} A^{-1}$$ e = V = \frac {work}{charge} = \frac {ML^...
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Why does a metallic piece very hot when it is surrounded by a coil carrying high frequency alternating current??
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Dec 30, 2016
Whenever high frequency alternating current is passed through the coil surrounding the metal piece i...
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A magnetic field of flux density $1.0 wb m^{-2}$ acts normal to a 80 turn coil of 0.01 m^2 area. Find the e.m.f induced in it, if this coil is removed from the field in 0.1 second.
answered
Dec 30, 2016
Given: $B_1 = 1.0 wb m^{-2}, N = 80$$ A = 0.01 m^2, B_2 = 0, t = 0.1s$$ e= \frac {-NA (B_2 - B_1)}{t...
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A conducting circular loop is placed in a uniform magnetic field B = 0.020 T with its plane perpendicular to the field. The radius of the loop starts shrinking at a constant rate of 1.0 mm/s. Find the induced e.m.f in the loop at an instant when the radius is 2cm?
answered
Dec 30, 2016
$\phi = \pi r^2 B$$ \frac {d\phi}{dt} = 2 \pi r . \frac {db}{dt}$when $ r = 2 \times 10 ^{-2} m \;\;...
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A conducting wire of 100 turns is wound over 1cm near the centre of a solenoid of 100 cm length and 2 cm radius having 1000 turns. Calculate the coefficient of mutual inductance of the two solenoids.
answered
Dec 30, 2016
Given: $N_2 = 100, N_1 = 1000$$ l = 1m = A = \pi r^2 = \frac {22}{7} \times (2 \times 10^{-2})^2 m^2...
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SI unit of magnetic flux is
answered
Dec 30, 2016
Ans: (b) Weber
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The magnetic flux linked with a coil is $ \phi = (3t^2 - 2t + 1) $milli weber. The e.m.f induced in the coil at t = 1 sec is:
answered
Dec 30, 2016
$\frac {d\phi}{dt} = 6t - 2$ (t = 1)$6 (1) - 2 = 4$ milli weber$ = 4 \times 10^ {-3} V$
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A wire of length 2m moves with a speed of 5 m/s perpendicular to a magnetic field of induction $0.1 wb/m^2$. The emf induced in the wire is
answered
Dec 30, 2016
$ E = Bl\upsilon$$ = 5 \times 2 \times 0.1$$ = 1V$
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votes
Amount of change induced in a circuit of resistance R is given by
answered
Dec 30, 2016
Ans: (b) $ dQ = \frac {d\phi}{R}$
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A solenoid coil has 50 turns per cm along its length and a cross sectional area of $4cm^2$, 200 turns of another wire are wound round the first solenoid co-axially. The two coils are electrically insulated from each other. Calculate the mutual inductance between the two coils.
answered
Dec 30, 2016
Given: $N_1 = 50$ turns /cm= 5000 l turn in l metre$N_2 = 200$$ A = 4 cm^2 = 4 \times 10^{-4} m^2$$...
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Two coils have mutual inductance of 1.5 henry. If current in primary circuit is raised to 5 ampere in one millisecond after closing the circuit, what is the e.m.f induced in the secondary??
answered
Dec 30, 2016
Given: M = 1.5 henrydI = 5Adt = 1 millsec = $10^{-3} sec$$ e = M . \frac {dI}{dt}$$ e = 1.5 \times \...
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An e.m.f of 250 microvolt in induced in a coil when current in it changes from 10A to 6A in 0.4 second. What is the self inductance of the coil?
answered
Dec 30, 2016
Given $ e = 250 \times 10^{-6} $ VdI = 10 - 6 = 4Adt = 0.45L = $\frac {e}{dI/dt} = \frac {250 \times...
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votes
As soon as current is switched on a high voltage line, the bird sitting on it flies away. Why??
answered
Dec 30, 2016
When the current is switched on, induced current flows through the body of the bird. The induced cur...
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The magnetic flex through a coil perpendicular to its plane and directed into paper is varying according to the relation $\phi = (5t^2 + 10t + 5)$ milliwebers. Calculate the e.m.f induced in the loop.
answered
Dec 30, 2016
Given: $\phi = (5t^2 + 10t + 5)$ milliweber$\phi = (5t^2 + 10t + 5) \times 10^{-3}$ wb$e = \frac {d...
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votes
A 2m long solenoid with diameter 4 cm and 2000 turns has a secondary of 1000 turns wound closely near it mid point. Calculate the mutual inductance between the two coils.
answered
Dec 30, 2016
Given: l = 2m, r = $\frac {4}{2} = 2cm = 2 \times 10^{-2} m$$N_1 = 2000, N_2 = 1000$$A = \pi r^2 = \...
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