NEET Physics Chapter Wise Mock Test – Magnetostatics EMI and AC, EM waves
The magnetic field of a given length of wire carrying a current for a single turn circular coil at centre is 6, then its value for two turns for the same wire, when same current is passing through it, is
A long solenoid carrying a current, produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is
Magnetic field due to 0.1 A current flowing through a circular coil of radius 0.1 m and 1000 turns at the centre of the coil is
(a) 0.2 T
(b) 2 x 10-4 T
(c) 6.28x 10-4 T
(d) 9.8×10-4 T
The magnetic field at a distance r from a long wire carrying current I is 0.4 T. The magnetic field at a distance 2r is
(a) 0.2 T
(b) 0.8 T
(c) 0.1 T
(d) 1.6 T
A charged particle of charge q and mass m enters perpendicularly in a magnetic field B. Kinetic energy of the particle is E, then frequency of rotation is
A charge q moves in a region, where electric field E and magnetic field B both exist, then the force on it is
(a) q(v x B)
(b) qE + q(v x B)
(c) qB + q(B x v)
(d) qB + q(E x v)
A beanri of electrons is moving with constant velocity in a region having simultaneous perpendicular electric and magnetic fields of strength 20 Vm-1 and 0.5 T, respectively at right angles to the direction of motion of the electrons. Then, the velocity of electrons must be
(a) 8 ms-1
(b) 20 ms-1
(c) 40 ms-1
(d) 1/40 ms-1
A straight wire of length 0.5 m and carrying a current of 1.2 A is placed in uniform magnetic field of induction 2 T. The magnetic field is perpendicular to the length of the wire. The force on the wire is
(a) 2.4 N
(b) 1.2 N
(d) 2.0 N
Two wires are held perpendicular to the plane of paper and are 5 m apart. They carry currents of 2.5 A and 5 A in same direction. Then, the magnetic field strength B at a point midway between the wires will be
(a) μ0/4π T
(b) μ0/2π T
(c) 3μ0/2π T
(d) 3μ0/4π T
An uniform magnetic field acts right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2 cm. If the speed of electrons is doubled, then the radius of the circular path will be
(a) 2.0 cm
(b) 0.5 cm
(c) 4.0 cm
(d) 1.0 cm
The work done in turning a magnet of magnetic moment M by an angle of 90° from the meridian, is n times the corresponding work done to turn it through an angle of 60°. The value of n is given by
Two bar magnets having same geometry with magnetic moments M and 2M, are firstly placed in such a way that their similar poles are on the same side, then its period of oscillation is T1. Now the polarity of one of the magnets is reversed the time period of oscillations becomes T2. Then,
(d) T2 = ∞
In which type of material the magnetic susceptibility does not depend on temperature?
A diamagentic material in a magnetic field moves
(a) perpendicular to the field
(b) from weaker to the stronger parts of the field
(c) from stronger to the weaker parts of the field
(d) None of the above
A magnetic field of 2 x 10-2 T acts at right angles to a coil of area 100 cm2, with 50 turns. The average emf induced in the coil is 0.1 V, when it is removed from the field in t second. The value of t is
(a) 10 s
(b) 0.1 s
(c) 0.01 s
(d) 1 s
A conductor of length 0.4 m is moving with a speed of 7 ms-1 perpendicular to a magnetic field of intensity 0.9 Wbm-2. The induced emf across the conductor is
(a) 1.26 V
(b) 2.52 V
(c) 5.04 V
(d) 25.2 V
If the number of turns per unit length of a coil of solenoid is doubled, the self-inductance of the solenoid will
(a) remain unchanged
(b) be halved
(c) be doubled
(d) become four times
A varying current in a coil change from 10A to zero in 0.5 s. If the average emf induced in the coil is 220 V, the self-inductance of the coil is
(a) 5 H
(b) 6 H
(c) 11 H
(d) 12 H
In an inductor of self-inductance L = 2mH, current changes with time according to relation I= t2e-t. At what time emf is zero?
(a) 4 s
(b) 3 s
(c) 2 s
(d) 1 s
A 100 mH coil carries a current of 1 A. Energy stored in its magnetic field is
Two coils have a mutual inductance of 0.005 H. The current changes in the first coil according to equation I=I0 sinωt, I0 = 10 A and ω= 100π rads-1. The maximum value of emf in the second coil is
In a circuit inductance L and capacitance C are connected as shown in figure. A1 and A2 are ammeters. When key K is pressed to complete the circuit, then just after closing key (K), the reading of current will be
(a) zero in both A1 and A2
(b) maximum in both A1 and A2
(c) zero in A1 and maximum in A2
(d) maximum in and zero in A2
In an experiment, 200 V AC is applied at the ends of an L-C-R circuit. The current consists of an inductive reactance (XL) = 50Ω, capacitive reactance (XC) = 50Ω and ohmic resistance (R) = 10Ω. The impedance of the circuit is
The current in self-inductance L = 40 mH is to be increased uniformly from 1 A to 11 A in 4 m-s. The emf induced in the inductor during the process, is
An L-C-R series circuit is connected to a source of alternating current. At resonance, the applied voltage and the current flowing through the circuit will have a phase difference of
Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?
(a) R= 20Ω, L=1.5 H, C = 35μF
(b) R=25Ω, L=25 H, C = 45μF
(c) R=15Ω, L=35 H, C = 30μF
(d) R=25Ω, L=15 H, C = 45μF
An alternating current generator has an internal resistance Rg and an internal reactance Xg. It is used to supply power to a passive load consisting of resistance Rg and a reactance XL. For maximum power to be delivered from the generator to the load, the value of XL is equal to
The primary winding of transformer has 500 turns, whereas its secondary has 5000 turns. The primary is connected to an AC supply of 20V-50 Hz. The secondary will have an output of
(a) 2V, 5Hz
(b) 200V, 500Hz
(c) 2V, 50Hz
(d) 200V, 50Hz
A step-up transformer operates on a 230V line and supplies current of 2A to a load. The ratio of the primary and secondary windings is 1 : 25. The current in the primary coil is
Direction (Q. NOs. 33-40): In each of the following questions, a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but the Reason is not correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false
Assertion (A): In an electromagnetic wave, the average energy density of electric field is equal to the average energy density of the magnetic field.
Reason (R): Electric and magnetic fields are related as E = cB.
Assertion (A): The electromagnetic wave is transverse in nature.
Reason (R): The waves propagates in straight line in vacuum.
Assertion (A): Two parallel wires carrying currents in the same direction, attract each other due to magnetic force between them.
Reason (R): They attract each other, if the currents flowing in them are in opposite direction.
Assertion (A): The torque on the coil is maximum, when coil is suspended in a radial magnetic field.
Reason (R): The torque tends to rotate the coil about its own axis.
Assertion (A): When a magnet is brought near iron nails, only translatory force act on it.
Reason (R): The field due to a magnet is generally uniform.
Assertion (A): Susceptibility is defined as the ratio of intensity of magnetisation I to magnetic intensity H.
Reason (R): Greater the value of susceptibility, smaller the value of intensity of magnetisation I.
Assertion (A): An inductance and a resistance are connected in series with an AC circuit. In this circuit, the current and the potential difference across the resistance lag behind potential difference across the inductance by an angle π/2
Reason (R): In L-R. circuit voltage heads the current by phase angle which depends on the value of inductance and resistance both.
Assertion (A): Inductance coils are made of copper.
Reason (R): Induced current is more in wire having less resistance.
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