Short Answer TypeA current is induced in coil C1 due to the motion of current carrying coil C2.
(a) Write any two ways by which a large deflection can be obtained in the galvanometer G.
(b) Suggest an alternative device to demonstrate the induced current in place of galvanometer.
Define the terms (i) drift velocity, (ii) relaxation time.
A conductor of length L is connected to a dc source of emf ε. If this conductor is replaced by another conductor of same material and same area of cross-section but of length 3L, how will the drift velocity change?Using Gauss's law obtains the expression for the electric field due to a uniformly charged thin spherical shell of radius R at a point outside the shell. Draw a graph showing the variation of electric field with r, for r > R and r < R.
In the circuit shown, R1 = 4 Ω, R2 = R3 = 15 Ω, R4 = 30 Ω and E = 10 V. Calculate the equivalent resistance of the circuit and the current in each resistor.
State Biot-Savart law, giving the mathematical expression for it.
Use this law to derive the expression for the magnetic field due to a circular coil carrying current at a point along its axis.
How does a circular loop carrying current behave as a magnet?Biot-Savart law states that the magnetic field strength (dB) produced due to a current element of current I and length dl at a point having position vector to current element is given by,
where, μ0 is permeability of free space.
The magnitude of magnetic field is given by, 
, θ is the angle between the current element and position vector.
Magnetic field at the axis of a circular loop:
Consider a circular loop of radius R carrying current I. Let, P be a point on the axis of the circular loop at a distance x from its centre O.
Let, be a small current element at point A.
Magnitude of magnetic induction dB at point P due to this current element is given by,
The direction of 
is perpendicular to the plane containing 
.
Angle between 
Therefore, 
... (2)
The magnetic induction 
can also be resolved into two components, PM and PN’ along the axis and perpendicular to the axis respectively. Thus if we consider the magnetic induction produced by the whole of the circular coil, then by symmetry the components of magnetic induction perpendicular to the axis will be cancelled out, while those parallel to the axis will be added up.
Thus, resultant magnetic induction 
at axial point P is given by, 
Therefore the magnitude of resultant magnetic induction at axial point P due to the whole circular coil is given by,
B = 
is the required magnetic field.With the help of a labelled diagram, state the underlying principle of a cyclotron. Explain clearly how it works to accelerate the charged particles.
Show that cyclotron frequency is independent of energy of the particle. Is there an upper limit on the energy acquired by the particle? Give reason.Show graphically, the variation of the de-Broglie wavelength ( λ ) with the potential ( V ) through which an electron is accelerated from rest.
In a transistor, doping level in base is increased slightly. How will it affect (i) collector current and (ii) base current?
When monochromatic light travels from one medium to another its wavelength changes but frequency remains the same, Explain.
Two convex lenses of same focal length but of aperture A1 and A2 (A2 < A1), are used as the objective lenses in two astronomical telescopes having identical eyepieces. What is the ratio of their resolving power? Which telescope will you prefer and why? Give reason.
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