A solenoid carrying a current supplied by a DC source with a constant emf contains an iron core inside it. How will the current change when the core is pulled out of the solenoid: will it increase, decrease, or remain the same?

A solenoid with an iron core and a bulb are connected to a.d.c.source. How does the brightness of the bulb change, when the iron core is removed from the solenoid?

A long solenoid having 450 turns per m carries a current of 1.6 A. At the centre of the solenoid a coil of 180 turns with cross sectional area 3.5 cm^(2) is placed having its axis parallel to the field produced by the solenoid. What will be the amount of induced emf when the direction of current in the solenoid is reversed within 0.03 s?

As shown in the figure, a rectangular loop of a conducting wire is moving away with a constant velocity v in a perpendicular direction from a very long straight conductor carrying a steady current I. When the breadth of the rectangular loop is very small compared to its distance from the straight conductor, how does the emf E induced in the loop vary with time t?

Self-inductance of an air core solenoid increases from 0.01 mH to 10 mH when an iron core is introduced in it. What is the relative magnetic permeability of iron?

A uniform magnetic field of 100 G (IG=10^(-4)T) exists in a region of length about 10 cm and area of cross- section about 10^(-3)m^(2) . The maximum current carrying capacity of a given coil of wire is 15A and the number of turns per unit length that can be wound round a core is at most 1000 turns m^(-1) . How would you utils the coil to design a solenoid for the required purpose ? Assume the core is not ferromagnetic.

A conductor in series with an ammeter and a semiconductor in series with another ammeter are connected in parallel. At a certain voltage both the ammeters register the same current. Will this condition remains as such if the voltage of the dc source is increased? Explain your answer.

A heating element of resistance r is fitted inside an adiabatic cylinder which carries a frictionless piston of mass in and cross-section A as shown in diagram. The cylinder contains one mole of an ideal diatomic gas. The current flows through the element such that the temperature rises with time t as DeltaT = alphat + 1/2beta t^2 ( alpha and beta are constants), while pressure remains constant. The atmospheric pressure above the piston is P_0 . Then the rate of increase in internal energy is 5/2 R (alpha + beta t) the current flowing in the element is sqrt(5/(2r)(alpha +betat)) the piston moves upwards with constant acceleration the piston moves upwards with constant speed

A long solenoid has 1000 turns per metre and carries a current of 1 A . It has a soft iron core of mu_(r)=1000 . The core is heated beyond Curie temperature T_(c) .