The magnetic flux linked with a coil is given by an equation Φ = 5t² + 2t + 3. The induced e.m.f. in the coil at the third second will be
(A) 32 units
(B) 54 units
(C) 40 units
(D) 65 units
(A) 32 units
(B) 54 units
(C) 40 units
(D) 65 units
(A) 32 units
The magnetic flux linked with a coil is given by the equation Ø = 2t² + 2t + 4 weber. The magnitude of induced emf at time t=2s will be
(a) 16 V
(b) 10V
(c) 12V
(d) 8V
A coil of wire of certain radius has 500 turns and self inductance of 75 mH. The self inductance of a second similar coil of 600 turns will be
(a) 100 mH
(b) 150mH
(c) 108 mH
(d) 105mH
The SI unit of inductance is the henry. It can be written as
(a) weber/ampere
(b) volt-second/ampere
(c) joul/(ampere)²
(d) ohm-second
In a circuit with a coil of resistance 3Ω, the magnetic flux changes from 1.0 Wb to 10.0 Wb in 0.3 s. The charge that flows in the coil during this time is
(a) 2.0 C
(b) 3.0 C
(c) 4.0 C
(d) 1.0 C
The direction of induced emf during electromagnetic induction is given by
(a) Faraday’s law
(b) Lenz’s law
(c) Maxwell’s law
(d) Ampere’s law
The self inductance of long solenoid cannot be increased by
(a) increasing its area of cross section
(b) increasing its length
(c) changing the medium with grater permeability
(d) Increasing the current through it.
Two currents loops are concentric and lie in the same plane. The current in the outer loop is anti clockwise and increasing with time. The induced current in the inner loop ,is
(a) Clockwise
(b) Zero
(c) Counter-clockwise
(d) None of these
In series R-L-C circuit, quality factor can be improved by
(a) decreasing L
(b) increasing C
(c) decreasing R
(d) decreasing R & L
Which of the following statements is not true about Gauss’s law?
(A) Gauss’s law is true for any closed surface.
(B) The term q on the right side of Gauss’s law includes the sum of all charges enclosed by the surface.
(C) Gauss’s law is not much useful in calculating electrostatic field when the system has some symmetry.
(D) Gauss’s law is based on the inverse square dependence on distance contained in the coulomb’s law.
Magnetic field lines form continuous closed loops
a) magnet is always a dipole
b) magnet is always a monopole
c) magnetic material is permeable
d) none of the above
Length of a hollow tube is 5 m, its outer diameter is 10 cm and thickness of its wall is 5 mm. If resistivity of the material of the tube is 1.7 x 10⁻⁸ Ωm, then the resistance of the tube will be
(a) 5.6 × 10⁻⁵ Ω
(b) 2 × 10⁻⁵ Ω
(c) 4 × 10⁻⁵ Ω
(d) None of these
\(10^6\) electrons are taken out of a pith ball. The positive charges on the pith ball is
A. 1.6x \(10^{-13}\) C
B. 1.6x \(10^{-19}\) C
C. 1.6x \(10^{-25}\) C
D. none of these
A charge Q is placed at the origin. The electric potential due to this charge at a given point in space is V. The work done by an external force in bringing another charge q from infinity up to the point is
(a) v/q
(b) vq
(c) v+q
(d) v
The direction of induced emf during electromagnetic induction is given by
(a) Faraday’s law
(b) Lenz’s law
(c) Maxwell’s law
(d) Ampere’s law