1 stat-Coulomb = ......... Coulomb

Two identical current carrying coaxial loops, carry current I in an opposite sense. A simple American loop passes through both of them once. Calling the loop as C,

Q factor of resonance is given by

Which of the following statements about electromagnetic waves is/are correct
(1) X-rays in vacuum travel faster than light waves in vacuum
(2) The energy of x-rays photon is greater than that of a light photon
(3) light can be polarised by x-rays cannot

The test charge used to measure electric field at a point should be vanishingly small.Why?

Why resistance becomes less in parallel combination?

Is the Resistance of Voltmeter larger than or smaller than the resistance of Galvanometer from which it is converted.

Why is spark produced in the switch of a fan when it is put off?

Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is 8.0 \(\times\) 10³ Nm²/C.
(a) What is the net charge inside the box?
(b) If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box? Why or why not?

In a meter bridge experiment balance point was observed at J with AJ-l

(i)The values of R and X were doubled and then interchanged. What would be the new position of balance point?

(ii)If the galvanometer and battery are interchanged at the balance position, how will the balance point get affected? 

Two identical circular loops P and Q, each of radius r and carrying equal currents are kept in the parallel planes having a common axis passing through O. The direction of current in P is clockwise and in Q is anti-clockwise as seen from O, which is equidistant from the loops P and Q. Find the magnitude of the net magnetic field at O.

At an airport, a person is made to walk through the doorway of a metal detector, for security reasons. If she/he is carrying anything made of metal, the metal detector emits a sound. On what principle does this detector work?

In an electromagnetic wave, the oscillating electric field having a frequency of \(3\times { 10 }^{ 10 }\) Hz and an amplitude of 30 V/m propagates in the positive x-direction.

(i) What is the wavelength of the electromagnetic wave?

(ii) Write down the expression to represent the corresponding magnetic field. 

Two Capacitors of capacitace 6\(\mu \)F and 12\(\mu \)F ae connnected in series with tha battery the volatage across the 6\(\mu \)F capacitor is 2 volt, Compute the total battery voltage.

The given graph shows the variation of charge q versus potential difference V for two capacitors \({ C }_{ 1 }\) and\({ C }_{ 2 }\) .The two capacitors have same plate separation but the plate area of\({ C }_{ 2 }\)  is double than that of \({ C }_{ 1 }\).Which of the lines in the graph correspond to \({ C }_{ 1 }\)and \({ C }_{ 2 }\)why?

An electric motor operates on a 50 V supply and draws a current of 15 A. If the motor yields a mechanical power of 150 W, estimate the power dissipated across its windings. Also find the efficiency of the motor?

A Rowland ring of mean radius 18 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field in the core for a magnetising current of 1.2 amp.?

why does a motor take more current when we start it?

Name the radiations of electromagnetic spectrum which are used in 

(i) warfare to look through fog.

(ii) radar and geostationary satellites.

(iii) studying the structure and properties of atoms and molecules. 

(i) Define electric flux. Write its SI unit. Gauss' law in electrostatics is true for any closed surface, no matter what its shape or size is. Justify this statement with the help of a suitable example.
(ii) Use Gauss' law to prove that the electric field inside a uniformly charged spherical shell is zero.

(a) Derive an expression for heat produced in a conductor for the flow of an electric current through it.
(b) What is the cause of heat produced?

Kamal's uncle was advised by his doctor to undergo an MR1 scan test of his chestand gave him an estimate of the cost. Not knowing much about the significance of this test and finding it to be too expensive he first hesitated. When Kamal learnt about this, he decided to take help of his family, friends and neighbours and arranged for the cost. He convinced his uncle to undergo this test so as to enable the doctor to diagnose the disease, he got the test done and resulting information greatly helped the doctor to give him proper treatment.
(a) What according to you, are the values displayed by Kamal?
(b) Assuming that the MR1 scan test involved a magnetic field of O.l T, find the maximum and minimum values of the force that this field could exert on a proton moving with a speed of 10 ms^-1. State the condition under which the force can be minimum.

Explain principle, construction and working of a.c generator.

State and explain Lenz's law. Give one example to illustrate the law. How will you verify it experimentally? Does it obey the principle of energy conservation?

Shyam and his younger brother were at the restaurant. It was very clean there. None of the flies and insects were there. His younger brother asked him about the fluorescent UV lamp present at the corner. Shyam explained the functioning of UV lamp, how flies and insects get trapped by it?
(i) What are the values shown by Shyam?
(ii) Give the source of UV-rays.
(iii)Give the harmful effect of UV-rays.

An electrical technician requires a capacitance of \(2\mu F\) in his circuit across a potential difference of 1 kV.A large number of \(1\mu F\)  capacitor are available to him each of which can withstand a potential difference of not more than 400 V.Suggest a possible arrangement that requires the minimum number of capacitors.

At room temperature copper has free electron density of 8.4 x 10²⁸ per m³. The copper conductor has a cross-section of 10^-6 m² and carries a current of 5.4 A. What is the electron drift velocity in copper?

A current of 500 \(\mu A\) deflects the coil of a moving coil galvanometer through 60^o . What should be the current to cause the rotation through \(\pi /5\)  radian ? What is the sensitivity of galvanometer ?

A resistor of 200 ohm and a capacitor of 15.0 \(\mu\) F are connected in series to a 220V, 50Hz a.c. source.
(a) Calculate the current in the circuit
(b) Calculate the r.m.s. voltage across the resistor and the capacitor. Is the algebraic sum of these voltages more than the source voltage? If yes, resolve the paradox.

(a) Suppose the windings of the armature in the d.c. motor of example 4 cannot tolerate a current of more than 20 amp. What do you think will happen if the armature gets jammed and cannot rotate when the motor is connected to the supply?
(b) If the supply connection of the d.c. motor in Ex.4 are removed and the motor is used as a generator by connecting the shaft of its armature to an external mechanical rotor of speed 3000 r.p.m., how much e.m.f. will be generated?

A laser beam has intensity 3.0 x 10¹⁴ M m^-2. Find the amplitudes of electric and magnetic fields in the beam.

Obtain the temperature ranges for ultraviolet part of radiation of e.m. waves. Use the formulae \({ \lambda }_{ m }T=2.9\times { 10 }^{ -3 }mK.\)  Take frequency of ultraviolet part of radiations as 8 x 10¹⁴ Hz to 5 x 10¹⁷ Hz.