Outline the differences between the magnetic fields produced by a solenoid and a bar magnet.

Describe the magnetic field of a solenoid.

A closely wound solenoid of 800 turns and area of cross section 2.5 × 10–4 m2 carries a current of3.0 A. Explain the sense in which the solenoid acts like a bar magnet. What is its associated magneticmoment?26. Explain resonance for an L-C-R series circuit and write its uses. In what kind of circuit willit possible?27. Obtain the expression of torque acting on electric dipole in uniform external electric field.28. Obtain the expression of electric field by a straight wire of infinite length and with linear chargedensity ‘l’

A bar magnet is moved towards a solenoid which is connected to a sensitive ammeter.  Which of the following will NOT occur as the magnet is moved towards the solenoid?A potential difference is induced across the solenoidThe lines of magnetic flux (magnetic field lines) of the bar magnet cut through the solenoidEnergy will be transferred from the bar magnet to the charges in the solenoidAn alternating current flows through the solenoid2Which of the following is NOT used in the construction of a transformer?A primary coilA soft magnetic coreA resistorA secondary coil3Which of the following statements is incorrect?When direct current is supplied to the primary coil of a transformer, an alternating magnetic field is produced around it (and within the core)The changing (alternating) magnetic field within the core of a transformer causes an alternating potential difference to be induced across the secondary coilIn a step-down transformer, there are fewer turns on the secondary coil than on the primary coilIn a step-up transformer, there are more turns on the secondary coil than on the primary coil4An alternating potential difference of 240 V is applied across the primary coil of a transformer.  If there are 600 turns on its primary coil and 30 turns on its secondary coil, calculate the potential difference across its secondary coil.12 V75 V4,800 V (4.8 kV)4,320,000 V (4.32 MV)5There are 1000 turns on the secondary coil of a step-up transformer and there is a potential difference of 2 kV across it.  There are 50 times fewer turns on its primary coil.  Calculate the potential difference across its primary coil.0.04 V0.1 V40 V100 V

A student is experimenting with a permanent bar magnet and a solenoid which has been connected to a sensitive ammeter.  He notices that a small current is registered on the ammeter as the magnet is moved inside the solenoid.  Which of the following will NOT increase the size of this induced current?Increasing the number of turns in the solenoidUsing a stronger bar magnetDecreasing the cross-sectional area of the turns of wire that make up the solenoidMoving the magnet into the solenoid more quickly2A student is experimenting with a permanent bar magnet and a solenoid which has been connected to a sensitive centre-zero ammeter.  She notices that the ammeter needle flicks to one side as the magnet is moved inside the solenoid.  Which of the following will NOT cause the ammeter needle to flick in the opposite direction?Moving the magnet into the solenoid more quicklyPulling the bar magnet out of the solenoidReversing the electrical connections to the ammeterRotating the bar magnet by 180° before moving it into the solenoid3A permanent bar magnet is moved towards a coil of wire which has been connected to a complete electric circuit.  The south pole of the bar magnet is closest to the coil as it is pushed towards it.  Which of the following statements does NOT apply as the bar magnet is moved towards the coil?The side of the coil which is opposite to the bar magnet will become an induced north poleWork is done by the charges inside the coil as the bar magnet is moved towards itWork is done by the bar magnet as it is pushed inside the coilThere will be a repulsive force between the south pole of the bar magnet and the induced south pole of the coil4What is the main energy transfer which occurs inside an alternator?Kinetic to chemicalElectrical to kineticChemical to kineticKinetic to electrical5Which of the following will NOT increase the potential difference induced across a rotating alternator?Increasing the magnetic flux densityDecreasing the number of turns in the coilIncreasing the area of the coilRotating the coil more quickly6Which of the following statements about dynamos is incorrect?A direct current will be induced in a dynamo which is rotated when connected to a complete electric circuitDynamos contain components called brushesDynamos contain components called slip ringsDynamos can be used to power light bulbs and other electrical components

f the number of turns in a solenoid is increased, the strength of the magnetic field producedwill