A 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.
Electric field intensity at a point outside a uniformly charged thin spherical shell:
Consider a uniformly charged thin spherical shell of radius R carrying charge Q. Let us assume a spherical Gaussian surface of radius r (>R), concentric with the given shell inorder to find the electric field outside the shell.
If is the electric field outside the shell, then by symmetry electric field strength has same magnitude Eo on the Gaussian surface and is directed radially outward. Also, the direction of normal at each point is radially outward. So, angle between
Therefore, electric flux through Gaussian surface,
Now, charge enclosed by the Gaussian surface is Q [Gaussian surface is outside the given charged shell].
Therefore, using Gauss theorem,
This is the required electric field outside a given thin charged shell.
If is the surface charge density of the spherical shell, then
Electric field inside the shell:
If is the electric field inside the shell, then by symmetry electric field strength has the same magnitude Ei on the Gaussian surface and is directed radially outward. Also the directions of normal at each point are radially outward. So angle between Ei and is zero at each point.
Thus, electric flux through Gaussian surface is 0 because of the absence of the charge.
The below graph shows 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?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.