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Showing 801 to 825 of 3046 questions (page 33 of 122).

801. Kirchhoff's first rule is based on the conservation of

A. flux B. charge C. mass D. energy E. momentum

802. A Wheatstone bridge is balanced when

A. the galvanometer reads maximum B. R1 R3 = R2 R4 C. R1/R2 = R3/R4 D. R1 R2 = R3 R4 E. R1 + R2 = R3 + R4

803. The resistance of a thermistor with a negative temperature coefficient

A. becomes zero at 0 K B. increases with temperature C. varies linearly with current D. is independent of temperature E. decreases with temperature

804. Maximum power is delivered by a cell of emf E and internal resistance r to an external resistance R when

A. R is infinite B. R = r/2 C. R = r D. R = 2r E. R = 0

805. The specific resistance of a conductor depends on

A. the current through it B. the nature of the material and temperature C. its length D. its area of cross section E. its shape

806. Two resistances of 6 ohm and 3 ohm are connected in parallel. The equivalent resistance is

A. 4.5 ohm B. 18 ohm C. 9 ohm D. 2 ohm E. 3 ohm

807. The force on a charge q moving with velocity v at angle theta to a magnetic field B is

A. qvB sin theta B. qvB cos theta C. qvB tan theta D. qB/v E. qv/B

808. The magnetic field inside a long solenoid with n turns per unit length carrying current I is

A. mu_0 I B. mu_0 I / n C. mu_0 n / I D. n I / mu_0 E. mu_0 n I

809. The SI unit of magnetic flux is

A. weber B. ampere turn C. tesla D. henry E. gauss

810. A charged particle moving parallel to a uniform magnetic field experiences a force of

A. half the maximum B. qvB C. qE D. zero E. maximum magnitude

811. Ampere's circuital law relates the line integral of the magnetic field around a closed loop to

A. the emf induced B. the enclosed current C. the flux through the loop D. the enclosed charge E. the loop area

812. Lenz's law is a consequence of the conservation of

A. mass B. charge C. energy D. momentum E. flux

813. The motional emf induced in a rod of length l moving with velocity v perpendicular to a magnetic field B is

A. Bv/l B. Bl/v C. B2vl D. Bvl E. B/vl

814. The SI unit of self inductance is

A. farad B. henry C. tesla D. ohm E. weber

815. The energy stored in an inductor of inductance L carrying current I is

A. LI B. L/I2 C. LI2 D. (1/2)LI E. (1/2)LI2

816. In a step up transformer

A. the secondary has more turns than the primary B. the secondary has fewer turns than the primary C. the secondary voltage is lower D. the secondary current is greater E. power in the secondary exceeds that in the primary

817. Eddy currents in transformer cores are reduced by

A. increasing the frequency B. removing the core C. using a solid iron core D. using a copper core E. laminating the core

818. The root mean square value of an alternating current of peak value I_0 is

A. I_0/2 B. sqrt(2) I_0 C. I_0/sqrt(2) D. I_0 E. 2 I_0 / pi

819. The resonant frequency of a series LC circuit is

A. 1/(2 pi sqrt(LC)) B. 1/(2 pi LC) C. 2 pi LC D. sqrt(LC) E. 2 pi sqrt(LC)

820. The capacitive reactance of a capacitor

A. is zero at all frequencies B. decreases with frequency C. increases with frequency D. is independent of frequency E. equals the resistance

821. In a purely inductive AC circuit, the current

A. leads by 45 degrees B. leads the voltage by 90 degrees C. is zero D. lags the voltage by 90 degrees E. is in phase with the voltage

822. The speed of electromagnetic waves in free space is

A. 3 x 10^10 m s-1 B. 332 m s-1 C. 1.5 x 10^8 m s-1 D. 3 x 10^8 m s-1 E. 3 x 10^6 m s-1

823. The power factor of a purely resistive AC circuit is

A. infinite B. 1 C. 0.5 E. 0.707

824. The SI unit of Young's modulus is

A. N m-1 B. N m C. N m-2 D. N m2 E. dimensionless

825. A solid in which the atoms have no long range order is called

A. amorphous B. ferromagnetic C. isomorphic D. polymeric E. crystalline

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